Being a human may be sufficient (with important exceptions) to play chess, but playing chess well is not sufficient to be a human.
Likewise with math, it turns out, it appears. Likewise with most other things we classify as needing intelligence, I bet. It turns out that intelligence is not the same as humanity or sentience etc..
But they're gaining more and more formerly exclusively human capabilities, increasingly advanced ones. The future isn't here yet, but good policy requires extrapolating and considering predictable consequences before they happen.