I concur to some level.<quoted text>
Cuneiform tablets have been discovered as far back a 3,500 BC, so Genesis could have very well have first been written 5,500 years ago.
The earliest cuneiform tablets were composed by the Sumerians titled the Enuma Elish amongst their other ones. They were very lenghthy in composition compared to only approx. 11 first chapters of the Hebrew Genesis.
The Sumerians were polytheistic.
So if the Genesis accounts were taken from the Sumerian ones then that would indicate the same with the Hebrews.
As archaeoplogy shows, the Hebrews prior to the 1st millenia were polytheists.