I do think that the Hermes theory makes sense but the choice of the name Jean really interests me. I was wondering if it was related to Jean-Marie in some way. Assuming that Jean-Marie went to Elysium (possibly) because of his good deeds and death in battle and his connection to the hotel, it's possible that Hermes brought him to the underworld or where ever his afterlife may be(Hermes is a psychopomp after all). If that's the case, we may be learning more about the gods and Jean-Marie from him.
Another option is that it is Jean-Marie in some sense. It's not out of the question that his spirit is bound to the hotel at least temporarily. Asterion said that he felt it when Jean-Marie died so maybe he is still tied to the hotel through a contract or something.
There is also the option that the name Jean is completely unrelated and he is just a shaman, decedent of an oracle, or something else entirely. The creation of the charms seems to suggest that shamans could very well exist in this world so having someone that may be more in tune with the less seen parts of the world could make them a valuable resource.
Sorry if I rambled a bit. I tried to keep it relatively brief because I have a lot of thoughts on this and a lot of possible theories, but I wanted to know more first since the evidence for all of these is somewhat lacking give how little we actually know about Jean and the current state of the gods.
Either way, I'm really excited to learn more and am looking forward to playing this update.