The original Disneyland was never supposed to exist in a world outside or realism. It was a fantasy / ideal version of reality.
At the magic kingdom, the flying elephants exist in a fantasized “storybook” version of a circus. They don’t exist in Main Street.
And as I mentioned, there is indeed a castle in Central Park in New York City, a castle leading to a carousel in a park (the hub of Main Street at MK is sadly not much like a park anymore but that’s a separate complaint) is again a fantasy version of the real world.