Yes it was God! There has always been a lot of curiosities about how the universe / earth / humans were formed. We know from here it was God :)
BUT, the world was originally NOT like what it is today - full of suffering, diseases, evil. There was no death or disease originally when Adam & Eve created, till they were banished from the Garden of Eden (Genesis 4).
Quite soon, in the Book of Genesis, we learn that God also makes laws for humans to obey! God is also the ultimate judge. The notions of "right", "wrong", "sin", "judgment" are real and serious. This is the part that many people do not like. They say who is "God" to tell me what is right and what wrong?!
And then, soon we learn that we should take God's word / laws very seriously! That is one very important lesson of Genesis 3 - "The Fall".
After the "The Fall", God did not give up on humans. But God faithfully pursued them, guarding on them (even though human lives have been marked with grave unfaithfulness / idolatry / rebellion from the days of Garden till today). We saw the first sign of it in Genesis 3, when Cain murders Abel but could not get away with it. (Yes, God did allow righteous Abel to be murdered by evil Cain. Why? - That is a separate conversation! Do read http://devos20xx.blogspot.com/2017/01/on-suffering.html).
A question that soon arises is that can humans be redeemed from the "The Fall" of Genesis 3?? We soon learn, after Genesis 3, that people are chronic sinners and cannot save or redeem themselves for the curse of "The Fall". Note, we see series of severe judgement in the Book Of Genesis:- Such as "The Fall" (Genesis 3), "Noah's Flood" (Genesis 7,8), "Judgement of Sodom & Gomorrah" (Genesis 19). But none of these eradicated sin & evil from human hearts. Rampant sin & evil on earth keep coming back (i.e., Genesis 4:8, Genesis 6:5, Genesis 11:1-7, etc), despite judgements from God.
So are humans then doomed forever from the "The Fall"? Thankfully, no, because of the love of God! Because humans cannot save or redeem themselves from the curse of "The Fall", God kicked off a plan to redeem the world via Abraham in Genesis 12. Again, knowing that people are unable to "save" / "redeem" themselves, God makes a "blood" covenant with Abraham (Genesis 15:9-21), that He ALONE will fulfill the promises He made to Abraham and his descendants (these promises actually amounts to redeeming the world after "The Fall" through Jesus). God did so by walking alone, instead of along with Abraham, through the path between cut sacrifice birds & animals. Some commentators claims that, in those times, the party that breaks a "blood" covenant is killed & cut like these sacrifice animals. If this is true then, perhaps, we see this fulfilled in Jesus being killed on the cross for the sins of people!
God is a God of broken & sinners. This is very well illustrated in the Book Of Genesis. The people God choose to carry forward the (arguably) most important, greatest & holiest plan ever (to save the world) were not always "seemingly" spiritual giants such as Joseph and Daniel. Often, God carried forward this plan through great sinners, such as Jacob and Judah (Actually from Adam & Eve to Abraham to Noah to Abraham to Isaac to Jacob struggled greatly with sin. But God still choose to work with them. ). For instance, Jacob was a very wicked man to start with. We have seen in Genesis 25 that Jacob would rather have his own brother dead so that he can have birthright. And in Genesis 27 he deceived greatly his own father & brother, even blasphemed by lying the name of God (Genesis 27:20). Such was a man God choose to work with, on arguably the most important plan ever.
Judah is another great example - He also did not seem to be serious about God to start with. He married a Canaanite, even though Abraham & Isaac forbid doing so (Genesis 24:3, Genesis 28:1) . He seeked prostitution (Genesis 38:16). He mistreated Tamar (Genesis 38). His apparent bad parenting may have led to the death of his two children (Genesis 38). He and his brothers sold Joseph as a slave. In the attempt to seek prostitution, Judah ended up sleeping with his daugther-in-law Tamar, which yielded a son Perez. Jesus choose to come through the line Perez who was a result of a scandalous encounter.
From the stories of people like Jacob & Judah, many sinners should have hope! Again all these stories reiterates that God is a God of broken & sinners. As Jesus said (Mark 2:17) "Those who are well have no need of a physician, but those who are sick. I came not to call the righteous, but sinners." However sinners must repent. We see repentance in the life of Jacob & Judah latter on. We do not see repentance in the life of Esau who was also a great sinner. As a results commentators do not believed that Esau is saved & redeemed like Jacob and Judah.
Incidentally the final lead person of God, Joseph, in the Book of Genesis is an anomaly! He stands out when compared to people of God who came before him or were along him. There is no "recorded" sin in his name! He is considered as a foreshadow of Christ by commentators. Maybe the point of this is that God chooses us sinners while we are still sinners. But our goal is to be Christ like, which is ultimately fulfilled when we have our glorious bodies - that is our final destination! Maybe "seemingly" perfect Joseph, who features at the end of the journey of Genesis after all these broken sinners, is a foreshadow of this destination of us!
We also see people of God being constantly thrown into great challenges, despite being God's people! This is in line with what Jesus said "In this world you will have trouble" (John 16:33).
God calls his beloved Abraham out of the comforts of his home & family into a journey ripe with great dangers. In the rest of Genesis this risky journey continues (i.e. with Isaac, Jacob, Joseph and others). We see God's people in great danger frequently (i.e. Abraham fears for life in Egypt - Genesis 15:10-10, Abraham battles with armies - Genesis 14, Isaac was about to be murdered - Genesis 22:10, Jacob's life was in danger - Genesis 27:41, Jacob was entrapped by Laban - Genesis 29-31, Dinah was raped - Genesis 34:2, Jacob's family get into serious trouble with Shechemites - Genesis 34, Joseph's is about to be killed and eventually sold as a slave and latter imprisoned - Genesis 37:12-36, Genesis 39, great famine endangers Jacob's family - Genesis 42).
What we also see, they richly experience God and His power during their trials (i.e. Genesis 39:2-6 - God is also made known and glorified). "As if" it is actually a very good place to be in, when you are hit with serious trials & sufferings. As then, also, you are very much dependent on God - again a very good place to be in! Remember how Paul boasts about his sufferings (2 Corinthians 11:16-33)!
One very interesting reality that you see is that God makes His people WAIT. Even though Abraham was very close & dear to God (In Isaiah 41:8 , God calls Abraham His friend!), God made him wait, apparently for more than two decades, till he had his first offspring (Genesis 21:2) promised by God in Genesis 12:7, at the very late & old age of 100. Imagine the emotional pain a parent goes through, waiting long for their first child. Righteous Joseph waited for thirteen years as slave and latter as a prisoner for freedom (Genesis 39-41), and more than two decades before his prophetic dreams (Genesis 37: 5-9) came true (Genesis 42:6). To Abraham and us it may seem God's plan to save the world has been unfolding very slowly, but Gods plan unfold in God's perfect timing. Sometimes they seem very slow to us.
Yes, it is sad that Adam & Eve lost their perfect bodies because of sin, and as a result we also have bodies that are grossly imperfect & perishable. But rejoice, we Christian will have better bodies than Adan & Eve upon resurrection! It will be better in the sense that we will be incapable of sin. 1 Corinthians 15:42-44:- "So is it with the resurrection of the dead. What is sown is perishable; what is raised is imperishable. It is sown in dishonor; it is raised in glory. It is sown in weakness; it is raised in power. It is sown a natural body; it is raised a spiritual body. "