No argument on the historical reality to that, unfortunately.
But since it’s a philosophical video, then I’d have to say that it’s a mistake to tie personhood to biological humanity at all. At minimum, I’d argue that it is analog rather then digital - that a human has more personhood than an ape which has more than… Otherwise you’d have to have some criterion to determine exactly which generation in our evolutionary history “counted.” It goes to zero somewhere before you get to something like a rock. Also, there’s not AFAIK good reason to suppose that such a scale has a maximum, or if it does, that modern humans are anywhere near it.
I’d also say that the logic isn’t necessarily circular so much as an infinite regress, like “common knowledge.” Minds are created already in motion, and recognizing one another is prior to self-awareness. Newborn babies will stare at faces and follow someone’s gaze and pay attention to mom’s voice yet still be startled when they mouth their own hands and feet.
