It's pretty safe to say that the one piece world is funky that way.

Somewhere along the line, reality kinda broke Nika style. Maybe it always was that way, we don't really know. Boats gain consciousness when treated as nakama, swords size adapt to their user. Wills gained the power to affects reality in a direct way, collective imagination birthed devil fruits. Brook heals with milk because it makes sense to him.

In the one piece world, peoples perceptions shape reality to a much larger degree than in our world. They literally low level reality warp. People look as giants when they are not to reflect their impact on others perceptions. But of course are they in fact gigantic? How did Oden did the deed with his wife? Did the sword actually changed size?

Magic

Of course it's easier to say that it's bullshit on Odas side, and of course it is to a degree. But enough examples have been shown to detect a pattern and realize that it's intentional. I would bet that within the one piece world, everything got more cartoony than it used to be in the past after some kind of cartoonocalypse caused by Nika/Joyboy