does the black goo, scarab, nanotech DESTROY the Alien canon?

I'm not sure if [i]the black goo, scarab, organotech DESTROYs the Alien canon[/i] but I have a suspicion we're all missing something truly essential, something fundamental that's altered the TIMELINE. Ready? The first Alien derelict, potentially thousands of years old, sat there on LV-426 waiting; warning all not to land. The first sacrifice Engineer to land on Earth, spilling his DNA after quaffing down black goo, scarrab, nanotech (it's all the same thing that breaks down them rewires to design) into our rivers and lakes. Maybe even causing a drinking party of proto-APES to mutate like Holloway and Fifield into what we now call Modern Humans. But this balck stuff, this genetic 'genesis' liquid ... it's been around for hundreds of thousands of years if it made (pre-humans) and millions of years if it made (dinosaurs). Wouldn't there be a 'chance' that THE ENTIRE GALAXY is riddled with this stuff? I mean, don't you just need like one drop of this tech to land on a planet to totally rewrite its ecosystem. I'm VERY CONCERNED about the timeline implication of such an 'accident', and I still don't understand the 'ancient eggs' under the laser shield of the egg chamber that were a) found on LV-426's Ganesha-driven derelict and b) mirrored or at least 'homaged' in Prometheus's bighead statued, reactive mural'd silo room. Anyway, that's it, no real 'theory', just an itchy feeling ... has the black goo BROKEN (or at least inadvertantly re-written) the Alien canon?