What does seem likely is that the human authors of Genesis 6-9, under divine inspiration mind you, and aware of the traditions about a Great Flood that preceded them and that existed in other cultures, traditions that suggest a certain viewpoint regarding the relationship between humans and God, crafted their own Great Flood story, drawing on similar motifs but radically altering the message. That seems unlikely. There is no evidence to support your claim, only speculaton. Do you think that maybe-- just maybe Genesis predates the other flood stories? Who sent the flood? The gods of Gilgamesh? It seems that those who find a relationship between Genesis and other ancient texts reject the idea of a worldwide flood. IOW presuppositions trump manuscript data. For a technical but fascinating examination of the evidence, see I Studied Inscriptions From Before The Flood, Ancient Near Eastern, Literary, and Linguistic Approaches to Genesis 1-11, Volume 4, 480pp. There are 25 scholars who contribute to this volume. Your position does not hold up.
I've requested the book via ILL and will review it. I trust you realize that academic discourse deals with varying degrees of probability and that it is not wise to blithely toss about the accusation of "speculation." Even the most tightly demonstrated and argued position, with evidence that will choke a cow, can be dismissed as "speculation" by those whose minds are closed.