Not strictly true, the mural more implies that they perhaps worship the xeno and are maybe tinkering around with it's DNA to create other creatures/WMD's.
The Xeno is a paratoid. Parasitic, it's origin is more likely conceived of by The Engineers as a weapon, as has been hinted at in the past. It takes on the traits of the being it comes in contact with and then aggresively overtakes the habitat.
The engineers are creators of life. It's more likely they designed this than found it on another planet.
Even then, them creating a living weapon used for terraforming is a far better story than, 'oh we found it and er just kept it around for kicks and studies (either of which isn't even told in the film anyways)'
are you sure you are not mistaking assumption for fact though, the mural sculpture is of a xenomorph yes but the reason for it being there are not yet explained. And although they were clear that Prometheus was not a direct sequel to alien, how does that also translate to the two more planned films not having some kind of more direct connection.
Because Spaights' was an Alien script, in interviews with both these writers they've said how Lindelof was brought in by the execs to 'de-alien' the film.
Execs have lost faith in the original franchise after the terrible sequels, they didn't trust the modern audience to attach to it, so they wanted a separate saga to make money from instead of your average audience seeing he trailer, seeing aliens and thinking 'oh not this rubbish again...'
The Deacon at the end of Prometheus is the humanoid Xeno form that goes onto being the catalyst for The alien films.
Lindelof - "I felt that the punchline of Prometheus was going to be that there is human DNA in what we have come to know as the human xenomorph."
Emphasis on Human Xeno, The Xeno that's depicted on the wall, it has arms and legs in proportion. it's a humanoid Xeno. As opposed to the dog, bull, fish, predator, etc etc we've seen depicted throughout the 'alien' mythos
He says it's open to interpretation whether this one goes onto be the Alien from the films, but that's hack writing.
I massively, doubt we'll see the Xenomorph in any of the follow sequels to Prometheus, that's the connection we got, The Deacon, and it was ****.
I could have written or even just mapped a much better tie in than Lindelof has in the end and still had a new franchise to milk that had no other link to Aliens.
You can pick holes in the theory, but as Lindelof said, it's all open to interpretation, and that isn't a good thing, and it's all he does, he's Vague and open ended, instead of being a brass balled writer and giving us a definitive on the focus. It's poor writing, and usually divides the audience, one says 'oh but we don't need all the answers and lets us think up our own interpretation'... The other says 'we've been sold half a story'.
And of course this is all speculation, but it's based of everything we've been told and shown so far *[ Can't wait for somebody to highlight just this line and say 'well that's it isn't it, it's your, like, opinion bro' offering **** all to the debate]*
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