But that`s the point, AVP has to be dethroned for a failure to lead the series. A false sense of loss in leadership was set up in Prometheus because they are absolutely playing with expectations. To some Prometheus failed to lead the series onwards (but this may be a plan to lower expectations for the sequel.. and then completely surpass them) Ridley even said the Alien was dead too, leading some to believe it would not appear, and really the old form didnt. It wasn`t scary anymore. AVP killed it. It belonged in Disney World according to Ridley, yet he brought what resembles an original alien back into the fray.
Again, sometimes to create something new (a new entry in the series, King alien) you must first destroy or break the old designs down and then use the elements in slightly different ways to allow it to build properly from a small beginning.
It`s about death and rebirth, not true immortality yet.
The creature had to be re-created as the Deacon after it died on screen and was almost completely destroyed in AVPR, bringing life back into the series by using the familiar form in a new way.
The black liquid accomplished this by giving it a new development and new forms.
Prometheus is all about being wrong and finding the opposite of what we expect so I have no probs being wrong with my theories, but this influences my theories heavily...
Instead of Gods we find mortal beings who still had some hand in our creation.
Instead of a Queen we find that a King will have his reign.
It`s as much an upgrade on the old worn out Alien design as it is AVP... The engineers may be looking to upgrade themselves too and seem to have gone bio-mechical by the end of the story.