I think one is conflating superset/subset privilege granting. Humans, a subset of things with backbones, are given the privilege of describing what is considere

I think one is conflating superset/subset privilege granting. Humans, a subset of things with backbones, are given the privilege of describing what is considered something capable of feeling and then extended it to all creatures with a backbone. This does not mean they've extended the privilege of labeling to all things with a backbone, only that they've ascribed a certain label to all things with a backbone. Similarly, humans labeling certain non-backboned creatures in this way does not ascribe those creatures the privilege of being considered human.