Humans should be included in movie, because Weyland-Yutani knew about Aliens before Nostromo crew faced them. What if previous crew was annihilated, so nobody could give a clue what's going on on LV-426 or some other planet or ship where humans encountered xenomorphs for the first time? WY decided to send 'collectors' (Nostromo) again, but this time with insider (Ash). Also what are Aliens? Just strange organisms discovered and gathered by Space Jockeys for further research, or powerful bio-weapon created artificially? This also raises question about Space Jockeys. Are they peaceful race or blood-thirsty warriors? Prequel could give a lot of answers and it should be exciting enough to 'wash' the bitter taste of Alien 3, Resurrection and AVP movies.