A proper identity solution is impossible.
I see three requirements:
1. Uniqueness: Exactly one ID assigned to each human
2. Irrevocability: nobody may invalidate the ID except it’s owner in the case of replacement
3. Anonymity: The owner of the ID can use it to prove their singular humanity without revealing anything else about themselves.
#3 is relatively easy to achieve provided #1 is solved. But #1 requires an Oracle [0] and cannot be decentralized to ensure #2 is upheld.
The only practical solution we’ve found is identity assignment by nation states, eg. social security numbers.