I think you people are seriously mixing things up. The Genesis is one thing, with heavy Babylonian influence, emerged probably during the Babylonian captivity, later edited in Israel. Maybe there was some basis to this which was general to all Semitic peoples but we don't know. There are good chances that there was nothing like the Genesis before the Babylonian captivity.
Then you have the tribal "forefather" narratives about Abraham and his family, which may be based on some ancient tribal tradition but most of it are very deep, very monotheistic moral and philosophical stories that could only have been conceived much later. The only thing that could really have ancient roots is the idea of a forefather called Abraham and of his lineage, which seems a pretty normal thing for any primitive tribe.
Then you have Exodus and everything that comes after. Note that the transition between this and the Abraham stories isn't very smooth. Suddenly this is not about Abraham and his family anymore but about a people, that somehow ended in Egypt but how exactly and why isn't very convincing, it seems the authors were struggling with that part. Suddenly we are in Egypt, there is a people, there is Moses who leads the people but the people seems to have an agenda of his own, doesn't always follow Moses, can act independently to some extent. This is a very different story written with a different purpose, which isn't very relevant for 2nd millenium Hebrews but very relevant for post-Babylonian captivity Hebrews. It takes a stand and gives answers on many issues that were relevant for Hebrews at this time: monotheism, role of prophets, place of the Hebrews in the world. This can only have been written much later than any date that could be attributed to the described events, and it is highly methaphorical and philosophical. The described Exodus is how an exodus should have undergone: an eschatological event ascertaining the special relationship of Hebrews to their God. Very different from the contemporary reality of a rather inglorious "exodus" of Jewish elites from Babylone when Cyrus freed them. This is the historical reference authors of Exodus had in mind, certainly not millenium-old stories about some "tsunami", even if we assume there were any. There were probably some tellings about a charismatical leader or a magician called Moses who was active during the times when the Hebrews were still nomads, and who had some connexion to Egypt(which in itself isn't surprising, because there was contact between the two peoples), but that's about it. Whatever was there, was completely transformed by authors for whom historical accurateness was the least of concerns. It seems pointless to try and establish any historical parallels between the described events(the plagues, the opening of the sea...) and history, at least beyond the very existence of a person called Moses. Maybe there were some parallels, but all of these things could have been made up just as well. They are methaphors, symbols.
Then you have Joshua and the invasion of Canaan, which is basically the story of a nomad tribe conquering land to settle itself there. Now from this point you do have an historical narrative, and this is probably the oldest part in the entire Bible. It's heavily deformed and mythologised, but it seems to be rooted in hard facts. From this point on, historical parallels begin to make sense. Not before.