"the great flood" is a metaphor for when the glaciers retreated, 8,000 years ago. The epic of Gilgamesh from Sumeria outdates the hebrew staple?bible by a full thousand years. They're clearly both about the same event, and the one from Sumeria is a thousand years older, so you decide....
But yeah, "when the glaciers retreated" could be used as well. Sea levels rose because the glaciers were melting/retreating and sea levels rose and that's how you get your flood.
But pretty much just the how the "red sea being parted" was really a REED SEA - i.e. MARSH
Shit gets built up over time and crazy loonies believe there's such a thing as "chosen"