... Dunno! That's a pretty loaded question! Super heavy! What makes "people"? And how can I say for sure what is or isn't in my dimension when the universe is so big, huh...? For all I know, there's Koopas walking around on a planet somewhere in another solar system!

[ it really isn't that complicated

but unfortunately, bowser asked that question to the alien conspiracy theorist, so it is apparently that complicated. ]