Arceus is the god of the Pokemon World.
Mew is like Jesus, except without a beard. And no resurrection.
Personally, I think the Pokemon Company just seriously hoped no one got that bored that they realised they stuffed up and created so many loopholes in the theory of Pokemon.
But that leaves the question of is it a Pokemon world with Humans or a Human world with Pokemon? Are Humans from another planet?
Questions for the universe in which supposably Arceus had something to do with.