The trailer, to me, seems to indicate an Alien prequel. The creatures looked an awful lot like the big thing they found on the planet with the chest burst open—before they found the eggs for the first time.
Ya same Alien “Space Jockeys”. Same type of ship as well, just like the derelict in Alien.
I believe that the premise that the original “Alien” xenomorph was a biological construct of the “Space Jockeys” and Prometheus explores the origins or purpose of these “engineers”.
Scott’s confirmation at the London press conference
that “Prometheus” will have to deal with the origins
of the Space Jockey. (big thing they found on the planet
with the chest burst open).