Its clear from many books of the Bible that they are not mythology but history. Babylonian and Sumerian accounts describe the creation as the product of a conflict among finite gods. When one god is defeated and split in half, the River Euphrates flows from one eye and the Tigris from the other. Humanity is made of the blood of an evil god mixed with clay. These kind of stories are expected when an historical account becomes mythos.
Actually the Babylonian and Genesis creation accounts have many similarities. Comparison here:
Comparing the Genesis and Babylonian stories of creation
Also the Gilgamesh epic (Babylonian flood story) is very similar to the Noah story. Comparison here:
COMPARISON OF BABYLONIAN AND NOAHIC FLOOD STORIES
How likely is the Genesis account to be derived from these accounts? The evidence supports the view that the biblical accounts turned into myths.
That is what conservative Christian theologians say. Liberal Christian theologians say the exact opposite: that the Babylonian accounts predate the biblical accounts. The archeological data appear to support the liberals. See the above links.