At some time around 2300 BC, give or take a century or two, a large number of the major civilisations of the world collapsed, simultaneously it seems. The Akkadian Empire in Mesopotamia, the Old Kingdom in Egypt, the Early Bronze Age civilisation in Israel, Anatolia and Greece, as well as the Indus Valley civilisation in India, the Hilmand civilisation in Afghanistan and the Hongshan Culture in China - the first urban civilisations in the world - all fell into ruin at more or less the same time. Why?
You make a good case with these empires falling simultaneously. A lot of this flood/creation stuff I chalk up to bad date-setting myself. Years ago, I remember reading a "Biblical Archeology Today" article on some excavations taking place in the city of Jericho. IIRC the archaeologists did find evidence of Jericho's city wall having been destroyed, but the dating of the damage/reconstruction didn't match their expectations for when Joshua led the Israelites against that city. Their conclusion (ready for this?) was that Joshua 6:20 wasn't factual, and that when Israel laid siege to that city, there was no supernatural event that brought the walls down. No mention was made that their dating of the ruins might be in error, which (if adjusted) would make the damage found match up with the account in Joshua!