I think you did a good job with the mystery of Jean. While one of my initial thoughts was that he is an agent of Hermes, I didn't speculate that he himself would be Hermes until closer to the reveal. I was overanalyzing Jean so much that one of my lesser hypothesis was that Jean might just be a red herring with that fact hidden in plan sight with his red shirt and he would just be a regular human and everything around him would just be a complete coincidence. Another thing I had considered was that maybe Jean was an agent of Aphrodite and he's actually Cupid/Eros playing matchmaker by gathering certain people to the hotel after his poking and prodding of Asterion and the MC's relationship. That conversation now makes me wonder which of his children was Jean talking about? I'm speculating it's Hermaphroditus.
This game has gotten me more into researching ancient Greek literature and mythology than my all of my life's schooling.