Interesting to see that the Denisovans mated with the Neanderthals, neither would be genetically compatible with the human genome. Cro-Magnon man is our genetic ancestors and the Neanderthals died out without mating with Cro-Magnon, at least from the genetic code that they have been able to determine, but they did co exist for a period of time. Or we can believe Zacharia Stitchen and the story of creation written from the Sumerians. Its all a good read
My guess is that the Sumerians 'acquired' their creation story from an even more ancient and lost (to us) civilization.