Is this proof David DID NOT Create the Alien..?

That's how I always understood it, David improved on what was already available.

thats how I always thought of it too. the problem is that casuall viewers don't see it that way. I hope awakemimg will make that more clear to the general public

David found an Engineer egg and this egg is shown for a second in the movie - he touches it before he leads Oram to the chamber. (Not the sliced one.)

The chamber eggs were created by David.

So it is probable that the eggs in the Derelict were made by the Engineers:

http://www.alien-covenant.com/topic/46741

I'm starting to agree that David and Engineer eggs/facehuggers/chestbursters are different.  Maybe David for the eggs and faehuggers already as we know them from the 1979 versions, because that's what the Engineers created and used.  Those facehuggers plant the regular embryo, leading to a snake-like chestburster with no arms or legs, leading to a biomechanical xenomorph (like the original).  When David says he perfected it, maybe he means he changed it so the chestburster is born with arms and legs already  so that it can defend itself right away like the protomorph.  So maybe the next movie war part will be Davi's fleshy, thin xenos vs the Engineers' slower, more plotting, bio-mechanical xenos.  I like it.

Well this is the Ambiguous Element of the Franchise, its open for them to explore either route.. more so if you read into the Book, but then the movies are to be considered True Canon.

So it means they can explore it in a number of ways..

1) David Created the Precursor to the Xenomorph and the Engineers Evolve it.

2) David Evolves the Engineers Creation (Xenomorph)

I do think RS is going for David as the Creator however, but we know if so, his Xenomorph has to become more Aesthetically like the 1979 Xenomorph and has to get onto a Engineer Ship in their Thousands (Eggs) that just happens to be very close to LV-223

Thus..... Engineers and LV-223 i think will become the Final Pieces of this Puzzle.