Here's an article from the Jewish Theological Seminary, about Jewish thought regarding Moses not being able to enter the promised land: The Sin of Moses (jtsa.edu) [note: one of the references says 'Shemot'; it's a slight slip, because it's the Jewish way of calling the book of Exodus (the author cites it as 'Exod.' for the rest of the article)]

From the Christian perspective, an additional aspect of it can be considered when we read how St. Paul considered the value of that rock that Moses struck twice instead of talking to it, as God told him (cf. Nm 20:7-8): “and all drank the same spiritual drink. For they drank from the spiritual Rock that followed them, and the Rock was Christ.” (1 Cor 10:4; emphasis mine)

And as an additional consideration from the letter to the Hebrews (referring to Moses, and many other people in the Old Testament at the start of chapter 11, on faith; the verses that follow are the closing verses of the chapter): “Yet all these, though approved because of their faith, did not receive what had been promised. God had foreseen something better for us, so that without us they should not be made perfect.” (Heb 11:39–40). The footnote from the New American Bible explains: "Hebrews 11:40 'So that without us they should not be made perfect': the heroes of the Old Testament obtained their recompense only after the saving work of Christ had been accomplished. Thus they already enjoy what Christians who are still struggling do not yet possess in its fullness."

Human sacrifice was a known pagan practice; that may also be part of why Abraham's trial of faith (this was still way before the time of Israel, and so this event in Abraham's life has to be taken in its proper context) was not about sacrificing Isaac per se --the people of that time were already somehow 'familiar' with the practice--, but that Isaac was his only son and the promise of descendance should be coming from Isaac; and so sacrificing him would really be hard to understand from only the human and practical point of view (and so precisely the trial of faith).

That aside, at a totally different level, later on with the events in Egypt and the Exodus, Israel was prone to easily adapt the pagan practices of the people around them. That was also true even when they already settled in the land. One of the known pagan human sacrifices there was to burn children, e.g. to the idol 'Molech' (cf. Lev 18:21; 20:2–3) or to the idol 'Adrammelech and Anammelech' (cf. 2Kings 17:30-31).

Israel seemed to follow this practice more notably during the time of the later kings. Solomon himself fell into endorsing the cult to Molech (1Kings 11:7). Generations after, King Josiah (one of the very few good kings of Israel) tried to do something about it (2Kings 23:10); but the practice was still there even leading up to the Babylonian exile, despite the constant admonition of the prophets (Jer 32:35; Ezek 16:21; 20:31). I guess it's with the fall of Jerusalem and the Babylonian exile that Israel finally learned its lesson: the hard way, as their deeds deserved.

'New Israelites' in the sense of new members of the worldwide covenant family that God had always planned for humanity, with Israel as the firstborn. We do not 'replace' Israel. Israel just suddenly had many more brothers after the saving work of Jesus Christ; the concept of 'Israel' now becomes much wider.

Following this analogy, perhaps how Israel reacted to the Church might be like how an only child had other siblings after some time as the 'only child', and wasn't too comfortable about the feeling that he no longer has the father's full and undivided attention as before; and so he somehow rebels against the fact, while trying to grapple with what all this now means for him.

Anyway, that's just how I thought about it. But it won't be me, but St. Paul who would have a better and deeper say in this, so I invite you to read Romans 9-11. At least from Romans 11, these considerations from St. Paul are mind-blowing:

“Now I am speaking to you Gentiles. Inasmuch then as I am the apostle to the Gentiles, I glory in my ministry in order to make my race jealous and thus save some of them. For if their rejection is the reconciliation of the world, what will their acceptance be but life from the dead? If the firstfruits are holy, so is the whole batch of dough; and if the root is holy, so are the branches.

But if some of the branches were broken off, and you, a wild olive shoot, were grafted in their place and have come to share in the rich root of the olive tree, do not boast against the branches. If you do boast, consider that you do not support the root; the root supports you. Indeed you will say, “Branches were broken off so that I might be grafted in.” That is so. They were broken off because of unbelief, but you are there because of faith. So do not become haughty, but stand in awe. For if God did not spare the natural branches, [perhaps] he will not spare you either. See, then, the kindness and severity of God: severity toward those who fell, but God’s kindness to you, provided you remain in his kindness; otherwise you too will be cut off. And they also, if they do not remain in unbelief, will be grafted in, for God is able to graft them in again. For if you were cut from what is by nature a wild olive tree, and grafted, contrary to nature, into a cultivated one, how much more will they who belong to it by nature be grafted back into their own olive tree.

I do not want you to be unaware of this mystery, brothers, so that you will not become wise [in] your own estimation: a hardening has come upon Israel in part, until the full number of the Gentiles comes in, and thus all Israel will be saved, as it is written: “The deliverer will come out of Zion, he will turn away godlessness from Jacob; and this is my covenant with them when I take away their sins.” In respect to the gospel, they are enemies on your account; but in respect to election, they are beloved because of the patriarchs. For the gifts and the call of God are irrevocable. Just as you once disobeyed God but have now received mercy because of their disobedience, so they have now disobeyed in order that, by virtue of the mercy shown to you, they too may [now] receive mercy. For God delivered all to disobedience, that he might have mercy upon all.

Oh, the depth of the riches and wisdom and knowledge of God! How inscrutable are his judgments and how unsearchable his ways!” (Rom 11:13–33)

Isaiah also expresses universality in Israel in a striking way: “It shall come to pass in the latter days that the mountain of the house of the LORD shall be established as the highest of the mountains, and shall be lifted up above the hills; and all the nations shall flow to it, and many peoples shall come, and say: “Come, let us go up to the mountain of the LORD, to the house of the God of Jacob, that he may teach us his ways and that we may walk in his paths.” For out of Zion shall go forth the law, and the word of the LORD from Jerusalem. He shall judge between the nations, and shall decide disputes for many peoples; and they shall beat their swords into plowshares, and their spears into pruning hooks; nation shall not lift up sword against nation, neither shall they learn war anymore. O house of Jacob, come, let us walk in the light of the LORD.” (Isa 2:2–5)

We can also consider how St. John's vision of the heavenly Jerusalem. The structure comprised both the 12 tribes of Israel (Rev 21:12) i.e. Old Testament, and the 12 apostles (Rev 21:14) i.e. New Testament.

You can check the auxiliary resource from Lesson 6, which is a document entitled 'from the Breviary - on Christ blessing the just men of old'. That's how ancient homily for Holy Saturday imagined Christ coming down to the place of the dead to bring out Adam himself and also the other just persons who died before the coming of Christ.

Hebrews 11 is also a long consideration of these things. The footnotes from the New American Bible explain thus: "This chapter draws upon the people and events of the Old Testament to paint an inspiring portrait of religious faith, firm and unyielding in the face of any obstacles that confront it. These pages rank among the most eloquent and lofty to be found in the Bible. They expand the theme announced in Heb 6:12, to which the author now returns (Heb 10:39). The material of this chapter is developed chronologically. Heb 11:3-7 draw upon the first nine chapters of Genesis (Gn 1-9); Heb 11:8-22, upon the period of the patriarchs; Heb 11:23-31, upon the time of Moses; Heb 11:32-38, upon the history of the judges, the prophets, and the Maccabean martyrs. The author gives the most extensive description of faith provided in the New Testament, though his interest does not lie in a technical, theological definition. In view of the needs of his audience he describes what authentic faith does, not what it is in itself. Through faith God guarantees the blessings to be hoped for from him, providing evidence in the gift of faith that what he promises will eventually come to pass (Heb 11:1). Because they accepted in faith God’s guarantee of the future, the biblical personages discussed in Heb 11:3-38 were themselves commended by God (Heb 11:2). Christians have even greater reason to remain firm in faith since they, unlike the Old Testament men and women of faith, have perceived the beginning of God’s fulfillment of his messianic promises (Heb 11:39-40)."

And regarding the last 2 verses of Hebrews 11, “Yet all these, though approved because of their faith, did not receive what had been promised. God had foreseen something better for us, so that without us they should not be made perfect.” (Heb 11:39–40), the commentary explains: "the heroes of the Old Testament obtained their recompense only after the saving work of Christ had been accomplished. Thus they already enjoy what Christians who are still struggling do not yet possess in its fullness."

What we profess in the Creed is only with respect to Christ: that he descended to the dead, and on the third day rose again, and ascended into heaven. Nothing is said about 'exactly when' the just men of the Old Testament finally made it to heaven; that'd be one more of the questions we can ask the Lord when with his grace we make it to heaven as well.