You didn't have a lot of friends in Purgatory, right? Outside of Dean? So maybe we can both make new friends, like each other.

[ He doubts that there were a whole lot of nice monsters in Purgatory for Benny to befriend. Jack doesn't know what his life was like before that, so maybe he had friends back home before it all went wrong, but Jack is someone who seeks community. He hates being alone. Even if he and Benny are new to each other, he doesn't feel alone when the vampire is there, and that has value to him. ]

You're unique, but I doubt you're the only one. Especially with other worlds here. Maybe in another one, they're all like you.

[ Just because monsters are evil in theirs doesn't mean it's the end of the story in the universe. Jack is very open to the idea of meeting people here who are different in their world. It would be a relief, really, because he has no intention of continuing on his hunter ways, and he would feel obligated to do something if there were bad monsters here. This way he can hope for the best. For Benny most of all, now that they're talking about it, so he doesn't feel alone himself. ]

Stranger things have happened than us being wrong about an entire species.