The background characters are definitely human. Although I really want to see what Arcturians are like. C'mon, FOX! No more teasing!
Also, I warmed up to Alien 3 and dislike Resurrection (that's pretty much the common mindset, although Alien 3 is sharply divided). Either way, it's looking like Blompkamp is going with alternative universe, which I can dig. As long as he hires the right writers to go with his excellent visuals, the movie will succeed. I don't think anyone will expect it to be better than Alien or Aliens. They just want a movie that they feel does "justice" to the series. "Good enough" is better than shite (Resurrection, AVP, AVP-R) that we've had to deal with for years.