This is also explained in a different question about the Humans, however not as thoroughly.
Humans have been gone for over fifty years from their huge cities(such as Inferno). And the majority of the area that our wolves thrive, there weren't humans near there to begin with. Luce, Lakagigar, Shi, and Velo Esente know nothing of Humans. A few of them that were born elsewhere, may have heard a fairytale legend of them as pups, but no more than that. Quall, on the other hand, travelled all the way across the continent (during the century of their 'reign of terror') and they had come across humans. They killed humans just as if they were any other sort of prey. And then, all of a sudden, they were gone. Quall has the lasting 'legend' that they were the ones that killed off the Humans. And now it's just a myth that most Quall wolves see as a way of empowering themselves(Our ancestors destroyed the rulers of the world. We ARE the best).
Obviously Rumsen Neshoba knows that humans still exist, since there are humans in the tribe! And the wolves of Inferno know of the humans, the ones that have visited Rumsen Neshoba, and the others that haven't visited only know of the legend of their existance.