I have seen several of the Alien movies and Prometheus but in none of them do they ever mention anything of the alien's home planet. Recently a friend claimed that they came from a far away planet where they were the bottom of the food chain and fled to survive. Is this true? If not where did they come from?
In Prometheus, the crew posit that the Engineers created the black goo that (at the end of the film) gave rise to a Xenomorph.
As the Xenomorph's are bio-engineered they have no home world, though the black goo that they eventually evolved from was probably originally created on the planet in Prometheus (certainly much of the research/experimentation appeared to be done there, probably safely away from the Engineer's home world) then that planet (LV-223) could be considered to be their home world in the sense of "their planet of origin".