Every place on earth has some legal definition of who is human. The system I’m thinking of isn’t a technical/captcha one, it’s a human curated list of humans. Just an electronic ID. Those already exist but the challenge is making them (acceptably) privacy-preserving.

I want to take my existing national digital ID and use it online basically. BUT I don’t want the websites to know it’s me. Just that I’m human (or perhaps over a certain age). And I don’t want the ID issuer to know what site/service asked whether I’m a human or I’m 18 etc.