Look at Arceus’ Midsection.
We all know that the Poke-God has that weird halo around its midsection, and it has some significance. In the anime, that same halo manifests as the Red Chain on Dialga and Palkia.
Now, going to focus on its myth, Arceus is reported to have “come from an egg”.
Here’s an excerpt:
I have reason to think that that egg never hatched - that egg is simply Arceus itself, with the horse-like body being extensions of the ends of that egg. The egg wasn’t explicitly stated to have hatched, either. This is further supported by Arceus’ mechanical movements and visor/helmet-like ‘face’. Notice how every part of Arceus’ body originates from the egg, especially the legs. They don’t come from the front of the body and instead are drawn directly attached to the ends of the egg where Arceus’ body ‘pinches’ to keep the egg’s shape in tact.
We also know that very balanced stats like Arceus’ belie a true, more powerful forme.
Thus I think that Arceus isn’t the ‘god’, but instead it HOUSES God.