The first parts of Genesis, from the tale of Creation through the tales of Adam and Eve, the Garden of Eden, the Tower of Babel, the Great Flood, Sodom and Gomorrah, the Wars of the Kings in which Abraham was involved -- are all based on earlier Sumerian records. The origin of the Biblical seven days of creation is almost certainly the seven tablets on which the Enuma Elish was written. This is evident from the contrast between the first six Babylonian tablets describing Marduk’s acts of creation and the seventh tablet which is dedicated to a general exaltation of the god (and thus a parallel to the Biblical seventh day when God rested).
During the last one hundred years, tens of thousands of clay tablets have been excavated in ancient Mesopotamia (modern day Iraq) dating back to 6,000 years ago. Archaeological and linguistic studies trace the origin of the Elohim concept to a Babylonian epic text known as the Enuma Elish, which deals with the creation of the heavens and Earth by a Babylonian God named Marduk. There is amazing similarity between Genesis and the Enuma Elish except that one credits the creation of heavens and Earth to God, whilst the other credits it to Marduk.
The HEBREW, EXILED IN BABYLON, WERE INFLUENCED BY THE ENUMA ELISH, which had been the most sacred Babylonian ritual text for over a thousand years.”
The earliest books of Genesis were handed down from generation to generation by oral tradition, before the Hebrew people developed a system of Phoenician writing, around 1000 BCE. So the Hebrews remembered bits and pieces of the Sumerian texts and wrote them down ADDING THEIR TWISTS AND SPIN ON IT when they learnt how to write.