Just how stupid were the ancient Israelites?

[Minimalist]

It's all symbolism, imho. A story told to convey a certain message. Maybe there was slavery of the Jews in Egypt and a man named Moses who helped lead them to freedom, but if that's the case, the story, as it is told, is exaggerated to make a point.

Both Redford and Finkelstein have zoned in on the late 7th century as the origination date for the exodus tale.  Of course, we don't know exactly when it was finally edited but geopolitically what was going on at the time was that the Assyrian Empire - of which Judah had been a loyal vassal - was collapsing under attack by the Babylonians.  The Egyptians under the 26th Dynasty kings, Psammetichus and Necho, were allied with Assyria.  The Judahites seeing a power vacuum as the Assyrians retrenched had an idea to move into the vacated areas and gave themselves a mythical story as to how they had come into possession of the whole region in the first place.

Even the bible honestly tells us how that went!

29 wIn his days xPharaoh Neco king of Egypt went up to the king of Assyria to the river Euphrates. King Josiah went to meet him, and Pharaoh Neco killed him at Megiddo, as soon as he saw him.

Whacked, like a low-level mafia hood!  That's what happens when you are on the wrong side.