How are the Outcast either more humane or less humane then the citizens of Polker Flat who cast them out?
Uncle Billy is really the only outcast who is less humane. He steals the horses and leaves the outcasts to die in the terrible weather. The other outcasts prove to be more humane. The citizens of Poker Flat had exiled the outcasts and threatened them with death if they returned, so in a way, they are inhumane and also responsible for their deaths. The Duchess and Mother Shipton both befriend Piney and help to take care of her. Mother Shipton starves herself to save food for Piney. And Oakhurst shows he is humane by staying with and caring for the whole group even though he could have left them when he knew they were in danger. He keeps their identities quiet when Piney and Simpson arrive so as not to worry them.
Yes, the outcasts were definitely more humane than the citizens of the town, and this fact actually creates some of the irony of the story. In the end, when The Duchess and Piney starve to death, the text says that no one could tell which it was who had lived a life of sin and which was the pure young girl. Death had been the ultimate equalizer.