This does nothing to guarantee that the content was written or edited by a human. Because of the risk of key theft, it doesn't even guarantee that it was published by the human who signed it.
It is physically, philosophically, and technically impossible to verify the authenticity of digital content. At the boundary between the analog world and the digital world, you can always defraud it.
This is the same reason that no one ever successfully used blockchains for supply-chain authentication. Yes, you can verify that item #523 has a valid hash associated with it, but you can't prove that the hash was applied to item #523 instead of something fraudulent.