Laughable nonsense. Do you know any nonhuman person? Name an animal or an extraterrestrial whom you treat as a full-fledged person. No takers? Perhaps that's because there's just a teensy weensy bit of overlap between humanity and personhood.

Why, then, distinguish the two? Because there's evolutionary continuity between animals and people (giving animals some personal qualities, and humans some animal qualities), and because we can imagine nonterrestrial persons, as in science fiction.

I'm not assigning rights. I'm reflecting on the meta-ethical problem of how to justify the moral discourse, given the death of God.