Yeah, but if they were able to arm some of them (or even just Ripley) I suspect they could have shot and killed 1 Alien without losing TOO many of their numbers. The reason they all died is partly because they were unarmed and constantly fleeing.
Even if they waited until they believed Ripley's story and then made a concerted effort to flush it out and kill it, at worst they'd have lost Boggs, Rains, Murphy, Clemens, and Andrews.
Sure they're not trained soldiers, but obviously once Andrews bought it they started listening to Ripley. Ripley knows how to kill Aliens using guns, she mowed down like 6 in close quarters in the Queen's chamber with the same magazine and they almost got the drop on her. Dillon and Aaron probably know how to take care of themselves with a gun, and I bet at least a handful of the other prisoners have used a firearm before in their lives.
Point is I'm pretty sure that if the prisoners worked together they could have taken out 1 Alien using some guns.
But you're right about the narrative - in fact, wasn't there some script draft that had Hicks survive the EEV crash and he actually has a pulse rifle with some bullets, but manages to miss the Alien when he has the opportunity to shoot it?