Roads to Safe Places

I could imagine that for crowd shots they took generic villager rigs with customisable body parts to give it a little variety. That's actually an advantage of 3D animation. In traditional animation all you can do is re-use complete animation and multiply it in the same shot, maybe recolour it, but that's it.
In Disney's Hunchback they first used 3D models for the crowd scenes. If you pay attention to the crowd members instead of the individual foreground character animation you'll notice the generic background characters look pretty robotic and horrible. It's OK, though, because the scene focus isn't on them and they wisely shrunk or blurred them to make up for their lack of detail.