Moses
was given the information about the creation account during his time with God
on the mountain (two 40-day experiences).
The first five books of the Bible were called “the Law.” Moses was credited with writing the Law. Jesus even said in Luke 24:44:
He
said to them, “This is what I
told you while I was still with you: Everything must be fulfilled that is
written about me in the Law of Moses, the Prophets
and the Psalms.”
The
creation information probably based down orally, but Moses was the first to
officially write it down.