I am prepared for the shitfest in the comments following this

If you wish to make an apple pie from scratch, you must first invent the universe. So Arceus

You mean there is no WRONG answer

But if Mew is the genetic ancestor to ALL pokémon, doesn't that mean that either:
a) Arceus is not a pokémon
b) Mew was around before Arceus

There's an easy way to solve this problem, ask for more specification

Reading this gave me cancer.