The Sumerian Flood--Where do you think the Bible story came from?
All those people are interelated, and there are overlaps in their folklore.
It was the cradle of civilization, or actually, one of four cradles. I'm not surprised there are similarities in their creation myths, and I wouldn't be surprised that they might even refer to real events. But I don't think enough has survived, as either history or archaeology, to say with certainty what the origins of some of these tales are.