This isn't really a review of Prometheus, so much as it is a spoiler-filled retrospective of some things which may have been missed in the tulmut of awesome which was that film. What I mean is, I want to talk about some of the elements of Prometheus which add to the world/universe-building, and maybe draw one or two conclusions from there.
I am completely willing to be wrong about many of these points--particularly the conclusions I draw--but some of them are just facts on the
digital image film.
Ready? Did you catch that I said "spoiler-filled" above? Good. Let's go.
2) Alien and Aliens both take place on planetoid Acheron/LV-426. Prometheus is set on a planetoid designated LV-233. The events in Prometheus, while indicative of the kinds of things the Engineers have done (and will do), are in not necessarily directly connected to the events of the rest of the Alien series.
3) Every alien creature we see in Prometheus reproduces in the same way. EVERY. ALIEN. CREATURE. The snakes and the squid are the larval forms of things which both initially jam their alien wing wong down your throat, deconstruct your DNA, and use it to reproduce themselves. Where do they come from? Well, they come from interacting with the goo from the Vases. The snakes? They come from the worms we see when they walk into the storage chamber. The Squid? It's what happens when the goo interacts with human sperm and ova. Also? They all have acid blood.
4) In the very first scene, the Engineer ship leaves a planet, while the single Engineer waits for them to leave atmosphere. When they're gone, it opens a small vial filled with Black Goo, much like that in the storage vases, and then drinks the contents. The intimation is that humanity--or the particular strain of organisms that will Become humanity--then unzips the Engineer DNA and reproduces itself. Humans don't do the whole "face full of alien wing wong" thing, but there's a reason for that.
5) That bas relief in the main storage chamber was a cruciform Xenomorph.
6) There is no reason to think that the Engineers are extinct. The ones we see are all in cryo-stasis, possibly infected with something, possibly just...waiting. If there's power to the cryochambers, then they're probably still alive.
So what, right? Who gives a crap? Well, you should, because the implications of this are several-fold, and all potentially very important:
a) The creature we see at the end is not a Xenomorph. Not in the sense that we know them, anyway. It's the result of the Human/squid/Engineer transition. I would wager that the snake thing would have done the same, or similar. Note that the extended jaw is...different. More like a goblin shark than a traditional Xenomorph.
b) The Events on Acheron/LV-426 are the result of an accident. One of the Engineer ships crashed (look at the angle of the ship, in Alien, compared to how they're situated in Prometheus) as a result of transporting either A) the results of the Black Goo/Whatever-Xenomorphs-Used-To-Be hybrid, or B) Xenomorph eggs being used for testing, DNA extraction, modification, and the Creation Of The Black Goo (this would explain where the adaptive properties of the Black Goo come from). Either way, a Xenomorph woke up. Cue terror, death, and mayhem.
c) Humans are a weapon and an heir. "What happens when we do this?" is the general M.O. of the Engineers, with that question being constrained to weaponry, if the events of Prometheus are any indication. Every incarnation of the things created via Black Goo contact is something violent, destructive, and something which uses its fallen victims to augment itself. Every One. But we only once see what happens when the Black Goo directly interacts with the Engineers (in fact they wear really beefy protective suits to prevent it, in all other instances), and that result is humanity. We are they.
Rather we are to the Engineers as David is to Peter Wayland.
So. Take all of these things together, and what do we get? A whole lot of speculation. I mean a whole lot. But think about it:
If the Black Goo is a weapons-design system...
If it either I: Encountered the things which became Xenomorphs and thereby made the only Incarnation to retain the trait of adaptation via the incorporation of the DNA of the host, and hence perfect; II: Is made from their DNA...
If, regardless of provenance, the Engineers were striving to use the Black Goo create better and better weapons?
Well then maybe they weren't returning to Earth specifically to destroy humanity, but rather to test it. Maybe their thought was, "We made you in our own image, via the most perfectly adaptable thing we have ever created/found; let's see what you can do." The fact that we eventually encountered those things which the Engineers worshiped as gods, and which killed many (though not all) of them...was just a lucky fluke.
And if that's the case? Well then first of all, I pretty much just spoiled any sequel there may be, but second, and more importantly, I think that by the Engineers' standards, we're doing a pretty damn good job.
Or at least Ripley is.