If one wants to explore the expanded universe of “Alien”, one will find that Marvel Comics has started a new title based on “Alien” in 2021. In the sixth issue of that series, a cyborg pointed out that xenomorphs were made for a purpose other than divine revenge. An android calls the animals “Prometheus’ cleansing fire”, implying that the aliens are used frequently to wipe out large swarms of creatures. Xenomorphs are used to keep any and all sentient populations in the bay.
Why are there so many creature extermination tools? While the comic doesn’t answer that question, it does explain a great galactic mystery summed up by the Drake Equation and the Fermi Paradox. The equation, named by Dr. Frank Drake in 1961, is a means of calculating the probabilities of other intelligent species in the galaxy. Given the sheer number of stars, it seems like human-like life would exist on other worlds. However, the Fermi Paradox suggests that if life could easily evolve on other worlds, then perhaps at least one alien species has invented interstellar travel and visited us. Indeed, it is absurd for them not to do so.
However, if there’s a genetically modified monster in the mix – and one specifically bred to wipe out the others – that would explain why no exotic species has encountered another. As soon as one species ascends to the stars, xenomorphs appear to kill them all. Then, once shaped, the xenomorphs revert to a dormant state in the egg until the next one.
With xenomorphs in the mix, Fermi’s paradox is solved!
https://www.slashfilm.com/1055257/why-xenomorphs-are-obsessed-with-killing-humans/ Why is Xenomorph obsessed with killing people?