Interesting question! Whilst you are waiting you can read some earlier threads that might be helpful.

You are certainly right that one should be sceptical of accounts written many centuries after the events they describe. In fact because of this historians are also questioning whether Moses was historical. In this answer u/Antiquarianism writes about the historicity of the Exodus and Moses. The same great user has also written more generally about the historical background and writing of the Hebrew Bible here. When it comes to Abraham, you can read this older answer by u/ScipioAsina which looks at the earliest evidence for belief in Abraham, and this more recent one by u/captainhaddock (great username!) which takes a sceptical view of the story of Abraham.

If you are interested in learning about similar stories of founders for various peoples for comparison, I can recommend some more threads. Our u/KiwiHellenist has written about the mythical founding of Greek peoples here and here, in the latter thread joined by u/itsallfolklore who comments on this from a folkloristic perspective, as you might expect. I have myself assembled a list of threads on Roman legends of their founding where my dear KiwiHellenist also took part: this can be read with this link. There is also this discussion by u/Iphikrates and others about the Iliad specifically and how similar stoies should be seen historically in general.