We have known two theories about the birth of mankind- Creationism and Darwinism. While one has too many flaws to be plausible, the latter doesn't answer all the questions. I have not given this subject much thought to be honest and the idea of another theory never even occurred to me. As suggested by the movie, if Engineers, as we refer to them, indeed created us, it doesn't stand next to the two existing theories as a third. But it simply replaces the God in creationism with Engineers. Now what good is that? Of course, good or bad is not even the question here.
We are told that Elizabeth Shaw is infertile, but a life is created in her. By this, how strongly are they indicating that Earth was barren before the arrival of the 'Engineers'? The movie only dares to attempt answering questions about the birth of mankind on Earth. It has no opinion on the creation of the Universe.It is indeed fascinating that humans, on their quest to find out about the species that created them, take along a species which they created. David has no soul. He has little regard for the value of human life even though he was created to serve them. He very casually does an experiment on a member of the crew and the results are frightening.
So now we have a robot attempting to learn more about humans by watching their dreams as they sleep in the Cryo, we have humans who are spending trillions of dollars and a good 6 years of their time, risking their life in the meantime, to find out about their creator, and the supposed creators, who we are told were far more advanced, may have done their own share of search for the one ultimate creator. A pattern emerges, and along with it, so many questions. Are we looking in the right direction? Is the search even necessary? Are we to assume that it was indeed a God who created everything and set this never-ending puzzle in motion? How did he come into existence then? What was before him?
Let's buy what it is trying to say. Engineers create Humans, and right after creating them, they abandon them, attempting to make contact (with the prehistoric men belonging to every civilization that formed from time to time) only to 'invite' them to their world. They, I assume, went away to explore other worlds, leaving behind some of what they possessed. If ever humans manage to reach this place, they knew they would revive the one person who was left behind in the Cryo. This would mean successful completion of their grand experiment. Now the humans will be either destroyed or mutated with the black goo (presumably alien semen) to create newer species. One chain leads backwards while the other leads forward. But this is extremely 2001: A Space Odyssey-ish. I don’t know, I believe this is right.
To support my theory, in the beginning of the movie, we are told that Prometheus was a mythological character who attempted to make humans equal to Gods, and for this he was killed. The spaceship Prometheus has done pretty much the same thing. It has made Humans, a mere product of a social experiment, on par with the creators or Gods, if you will. And the consequences will be dire.