In fairness, Genesis is the book of Jewish adaptions of Sumerian Myth. The Ark itself was the product of Sumerian myth (which made more sense because the God who wanted to kill everyone was a different being from the one who wanted to save humanity).

Most of the other books are Hebrew history. While these were told word of mouth for centuries before being written and were obviously subject to the phone-game effect, plus obviously hyped up... I think at least the broad events are more historically accurate.
To the ancient Sumerians, I think Mesopotamia = the world, so a flood there would be a flooded world.

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