Freud speculates at length on the possibility that Moses was killed by his own people, but it's curious he never brings up Cain and Abel, especially as Abel and Moses are both designated as shepherds. Maybe he didn't want to draw attention to the later guy.
The preservation of the Jews is the triumph of church over state; monotheism created these people, and they've seen a lot of empires come and go. When they went and made themselves a state, of their own will, without divine intervention, they gave up what made them a people in the first place. It's not to be wondered at that they are so smart; monotheism is the highest abstraction, and presumably the Exodus consisted in people who really believed.