By no means do I really understand the science behind this, but something just doesn't add up for me when thinking about the Engineers and Humans relationship.
So, the Engineers and Human Beings are a complete DNA match from what I understand.
The Engineers came to Earth and sacrificed one of themselves to start life, I do believe.
Now, If they seeded the beginning of life on Earth, doesn't that mean everything would be related to them, or a direct DNA match? Which would not make sense because as humans we aren't genetically related (or barely) to other organisms we share this planet with - aside from these 'Engineers'. And if Humans are a one hundred percent match - or close to it - wouldn't that mean we have gone through no genetic mutations to maintain such 'purity'. Meaning that the human species would immediatley have come to be after the Engineers sacrifice with little evoultion in between now and then. But then the theory of evoultion is thrown out the window and it is more of the Adam and Eve thing - maybe that's what Ridley wanted?
Or was life already in motion on Earth when the Engineers arrived, and the humans - sprouting from the Engineers - became an Alien species that was introduced to Earth, meaning we never evolved here to begin with until after the Engineers sacrifice?
F*** me, I'm confused. Someone unwind this...