It is common for Catholic apologists to claim they gave us scripture through the church councils. This couldn't be farther from the truth. The church councils were sometimes meetings of all christian sects combined into one, that is why they were termed catholic, it was a universal representation of all sects. Some good, some bad. Some gnostic. If you study the trinity wording for instance it came much from Plato and gnostic thought. The same terminology was used. I do believe in Father, Son, and Holy Spirit but not through the church councils. I also believe in the books of the Bible but not through the councils. They came through the Apostles and Prophets of the 1st century church.
Peter himself offers proof of this himself in his letters. The 2 Peter letter begins by addressing all of Christianity. All who have attained to like precious faith.
2 Peter 1:1
Simon Peter, a servant and an apostle of Jesus Christ, to them that have obtained like precious faith with us through the righteousness of God and our Saviour Jesus Christ:
It is a general letter to all of Christianity of his day who would undergo suffering through persecution. In this letter he mentions Paul's letters being scripture. That means Paul was attetested to by Peter and that means anyone rejecting Paul also rejects Peter. The letter says Paul wrote unto you.
Since Peter and Paul have the same audience we can infer Paul's writings were to all with like faith. Paul's letters were therefore for the whole Christian body. Thus this was a settled truth. Though they wrote for specific denominations and geographical locations, they were for all to learn. So, the early church grew up from earliest times respecting and knowing scripture. One could argue this leaves out men such as Luke or John who aren't mentioned, even the Gospels not mentioned specifically, but one verse covers them all.
2 Peter 3:2
That ye may be mindful of the words which were spoken before by the holy prophets, and of the commandment of us the apostles of the Lord and Saviour:
They were in posession of all the above. The words of Christ were preserved, the commands of the apostles and prophets preserved for their memory. So the 1st century church knew all and preserved all that was meant as scripture.
As the church spread many sects sprang up with differing false forgeries and writings, but the church surely knew the difference. The church councils didn't preserve the prophets but pressed into them the apocrypha and sometimes false gospels for a time. The standard view prevailed however and we still have
The words of Jesus
The commands of the apostles
The words of the prophets
So, these were stable before 65ADn and all scriptire before 100Ad. The church was already passing them forward. The churches of the 4th century didn't give or produce scripture. They could only do what all generations do, move them forward for the next generation.