Genesis was written 850 years after the death of Moses and after the Babylonian exile... which is very odd because they did have a written language. Sumer did in 3000 BC.. and the Akkadians who predate the Babylonians did.
Prove that Genesis was written 850 years after the death of Moses. No conjecture, no speculation, no assumptions.......just present the objective facts in evidence that proves that Moses had nothing to do with recording Genesis.
On the other hand there is much "prima facie" evidence found to exist in other parts of the scriptures that demonstrates that the first 5 books of the Bible were recorded by Moses.
Example: In Luke 24:27,44..........Jesus addresses the Law of Moses, Psalms, and the Prophets. In scripture the first 5 books are often called the LAW OF MOSES...or....THE LAW. The other 4 books that make up the Law of Moses are Exodus, Leviticus, Numbers, and Deuteronomy.
Simply because none of the record found in Genesis states that "Moses said".......is no indicator that Moses had nothing to do with Genesis, Moses was not alive during the record of Genesis, He is credited and referenced by the New Testament writers as the one who passed on this ORAL RECORD from peoples who lived before Moses......with Moses acting as the editor and complier of this record as directed by the Holy Spirit of God. The actual record certainly comes from people that lived before Moses.
However there is evidence found in the script of Genesis that indicates that Moses indeed was the inspired "editor" of Genesis. Throughout the Book of Genesis you find the Hebrew word "toledoth" being recorded with regularity. The word toledoth is translated to mean "These are the records of or this is the history of........." These are signature lines of various authors found in the Book of Genesis. As stated this is an oral history that Moses simply edited to script as inspired by the Holy Spirit.
Example Genesis 2:4 The records of heaven and earth....this is God's history of creation. or "TOLEDOTH"
Genesis 5:1 The TOLEDOTH of ADAM
Genesis 6:1 The TOLEDOTH of NOAH
Genesis 10:1 The TOLEDOTH'S of SHEM, HAM and JAPHETH
Genesis 11:10 The TOLEDOTH of SHEM
Genesis 11:27........Terah.........Genesis 25:12..........ISHMAEL..........Genesis 25:19......ISAAC........Genesis 36:1,9........ESAU........Genesis 37:2............etc., then begins the TOLEDOTH of EXODUS 1:1 .....the history of the children of Israel.
Again........present the objective, testable, reproducible evidence that proves anything predated God's history of Creation as found in Genesis. Its a most difficult thing to prove that something predated the Beginning.....since recorded History can calibrate things of the past 5000 years. Anything you present would by necessity of fact have to be based upon Conjecture, Speculation and Biased ASSSUMPTION....i.e., PHILOSOPHY (Opinionated Guess work). Anything before the 4th millennium would also have to be an ORAL HISTORY.....as mankind did not develop a written language before that time period in history.
en.wikipedia.org
As demonstrated.........the

scientific term for this historical GUESS WORK is called Epistemology......but guess work is still guess work. EPISTEMOLOGY: The "philosophical" ......"theory" of KNOWLEDGE.
Who do I personally choose to accept as documented truth.........The Holy Scriptures or your EPISTEMOLOGICAL GUESSWORK? I choose door number 1. The inspired words of the Holy Spirit of God. ".....but as for me and my house, we will serve the Lord." -- Joshua 14:15