If you're truly interested, peruse ...
The implication is that what we think of as Israel underwent dramatic population transfers which, among other things drove much of the scribal class south. Similar population reshuffling occurred in the wake of the Babylonian conquest and exile.
With the Persian victory, the desire was for a stable vassal state in Judah-Samaria, and that meant that the mixed multitude of that area begin to conceive themselves as a people with a mandate. What threads of Hebrew scripture were written by whom and when I do not know, but I suspect that the final redactions were post exilic, and that various forces competed to mold the characteristics of peoplehood that would finally emerge.
When you say ...
"I do think that there might be a historical incident, an escaping of slaves on a large scale which was magnified in to miraculous events."
... I'm simply suggesting that a far more impactful historical catalyst would have been the impact of Assyria, Babylonia, and Persia on a little strip of land that separated those major powers in the north from Egypt in the south.
Because of the "Bible" - however defined - we in the West view the area being discussed through a laughably distorting "Israel" lens. In fact, for most of its history, Judah and Samaria were bit players in a much, much larger stage.