Bodhicitta and the path of knives?

Is cutting off the "path of knives" (i.e. avoiding rebirth into lower realms) not the ultimate? I mean, obviously it's unlikely any Buddhist seeker would affirm that. But, given life on earth can be improved for humans, is it not very *like* the ultimate, to never again accrue evil karma and rebirth into hell or animal or ghost realms? Also, do any of the schools which say some sentient beings lack a seed for buddhahood, self enlightenment, and arhatship, claim that those sentient beings can forever avoid rebirth into the evil destinies? And in what way can they work for bodhicitta?