How could AI not make it look more like a man? Was the AI trained on lots of bigfoot footage? Or was it trained on lots of pictures of people? Give it enough leeway and it will probably render bigfoot as a man in a Barney costume, if that better confirms to the training data.

AI wasn't used to generate the clip, but to add some (hallucinated) detail and extend the background. FWIW, in pre-genAI stabilized examples from the 2000s it's also clearly a guy in a gorilla suit.