There are many different schemes of Proof of Human Work (PoH or PoHw), though https://www.miftycoin.com is the only one known to be a real implementation publicly available. In the case of MiftyCoin, block validation is perform by humans solving puzzles. Each puzzle is unique to each solver, as it is a function of the block identifier, the solver’s address hash and the transaction hashes.

A whitepaper on MiftyCoin can be found here:
https://arxiv.org/pdf/2211.14444

Disclaimer: I am the creator of MiftyCoin.