I guess you meant Egyptian not Sumerian. The Egyptians were those with Horus as the Jesus figure with the exact same story. The Sumerian stuff was about the Gods from another planet coming down and creating mankind to serve for them. You still have some loose ties to the Old Testament of the Bible which in the end is about the two brothers En'Ki and En'Lil fighting over what to do with the "slave race" mankind with all the banishment from Eden stuff and so on. At some point there was some kind of judgement making one of the brothers into god and the other one became iirc the snake and in general the sort of evil counterpart. That also explains why the God of the Old Testament doesn't really act that much "godlike" but often not different than a pissed off man with lots of power would...

Not trying to break your argument though as I tend to agree with what you're saying here...