As seems to happen so often when we read one question here, another comes to mind.
While I liked the original Alien and the first and third sequels (and saw all four), I never wanted to see Alien vs. Predator and I'm not up with all the details. And when reading this question it reminded me of another question that's bothered me for a few decades.
The facehugger seems to have evolved specifically to target a human face. It always seemed odd the Space Jockey's ship crashed, since it had a trunk, like an elephant, and the facehugger wouldn't work on that kind of face. Even on Earth, there are examples of species that a facehugger won't work on, like an elephant, or likely on a large snake (there's nothing to grab on to).
Is there any reason given, in-universe, for the reason why a facehugger seems to be such a perfect fit to humanoids? Is there a reference to a common host species on the alien's homeworld that is enough like humans that there was a parallel evolution? Or do we find out, at some point, perhaps, that humans were an intended target from the start?
Or is this just due to convenience from a production standpoint, with no in-universe explanation?