I am surprised no one has mentioned Imhotep - a deified historical person.
I would think that it is quite possible the memory of a great ancient ruler could be turned into the story of a god but I do not see how we could get evididence of it happening.

Well all of the Kings were divine, naturally - Horus and Osiris and all of that, as well as Aton or the son of Aton at least the once (though really, given the name of a palace of Amenhotep the Magnificent [? right?] it could have been more then just Akhenaten). There's also some theories that the whole Set vs Horus story arose from the conquering of a predynastic Egypt by a Dynastic race who sort of jump-started Egyptian culture, though those weren't just people themselves.

There were a few different historical persons who lived on in memory as demi-gods or gods - two of them are Amenhotep, son of Hapu, who was a scribe, and the previously mentioned Imhotep, the guy who designed the stepped pyramid.

As for the rest of the gods... well, I haven't really heard anything, which makes me a bit skeptical that many of them were based off of real people. I could be wrong, I suppose, but I think the majority of the Gods and Goddesses were themselves from the beginning.

About the Mesompotamian origins. I read about a river that flowed from west arabia to near Kuwait and dried up sometime between the end of the last ice age & the start of Egyptian civilisation. I have speculated that a ciilisation could have started there and migrated to modern Iraq and Egypt when it dried up.

i don't know about this river, do you have any keywords that i can search for?

It was a long time ago - I have tried seaching the net several times with no luck.

This looks pretty good; very ignored until now by Hollywood unless you count Stargate.

We just need a good Viking Gods movie I dont count Thor as a mythological movie

Plus theres talk of a new film of The Odyssey