But it doesn't change the fact? that the stories would have started out as oral tradition
Of course this is not
fact but opinion.
I am old enough to recall a time when people claimed that writing was invented
after the time of Moses, and hence he could not have been the author of Genesis. This led to the conclusion that the stories must have been handed down "around the campfire". I do not doubt that some of the flood stories around the globe were handed down by oral tradition and that this accounts for their mythological bent.
The Moses account does not sound that way to me. I prefer the idea that Moses, being a prince of Egypt, had access to ancient writings which I believe could have been written by the survivors of the Flood, perhaps Noah's sons, who might have written down details they remembered happening during the flood, perhaps working from daily recordings (sort of a ship's log). Of course this is speculation, but so is any other idea of how the stories got into their present form in Genesis.
The expressions still found in Genesis, "these are the generations of _____", seem to be a form of author signature, as explained in The Tablet Theory of Genesis Authorship.
http://www.ldolphin.org/tablethy.html