If we can take a step back from the long running theories of the past such as them being the apex predator on their planet the killed everything else or created as bioweapon to kill off a planetary population, what about this for consideration instead: it's also a long running concept that the xenomorph as we've seen it is not the final form and doesn't have to be. I like the scifi stories where the humans stumble into the middle of something far larger than themselves, discover small bits and pieces of it and struggle with those without knowing it gets far more complicated. The overarching makeup of the creatures is organic mixed with inorganic. They don't build singular ships staffed with xeno creatures all getting paid money with families they love back home, etc. They're hivemind creatures that send out spores/eggs into space on really long journeys (which aren't that long to them) towards habitable stars. When sufficiently advanced species stumble upon these spores, they get infected and eventually consumed. Or the spores land on life-filled worlds, whichever. The facehuggers, then xenos, then transformed into further biotechnology eventually using up all the organic mass to create a world suitable for the species as well as a wormhole hub that opens up back to the home system. This is how they colonize worlds and move star to star. The galaxy is big enough that their home system is still far away. The Space Jockeys are just a third party that ran across one of their spores and while studying it inadvertently triggered it before they could take it home. It didn't have enough biomass to do anything. It would be a neat take. The aliens don't have to just be mindless tiger monsters that want to claw everything, then hibernate, and that's all there is to them.