My Theory: Black Goo = The REAL Villain

Hypothesis (and apologies in advance if someone has previously posted this theory - I know I can't be the only person who's thought of it): What if the black fluid "came first"? It seems to move about of it's own accord, has an apparent "will", and is able to mutate whatever life forms it infects to it's own ends. Also, we know that the Space Jockeys are genetically identical to humans (though they sure don't look it). So. What if... A dwindling quantity of black ooze ("liquid Evil", in essence) found it's way to Earth, transformed primitive humans into "Space Jockeys" (much like it appeared to be doing to Holloway), imbued them with the knowledge and will to engineer/grow spacecraft that would carry them back to it's point of origin, where they could assist it in replenishing itself (and before departing, they of course, left "signposts" around the globe to entrap any unfortunate sentients who may follow in subsequent ages). Of course, the drawback is that too much of it is toxic, thus the "sacrificial" engineer disintegrates when he ingests more than his cells can withstand. And, similarly, generating a sizeable quantity (such as it would take to return and *infect* all life on Earth - perhaps the REAL "plan") ends up being lethal to the original (compartively minimal) "facility staff". It's something of a stretch, admittedly, but I do think that the overall plot tends to make a bit more sense when viewed from this angle.