I just did a re-read of Oda's short stories collections (Wanted, Monsters...)
And we see so much stuff in those stories we dreaded for One Piece
In the first Wanted short story, we see a ghost, and not some spooky crazy thing, but just a person that died and didn't wanna move on.
In the second story, we see an actual god that writes destiny, and Oda says he loves that story.
In the third story we also get another god, both this god and the one in the second story are very human-like, so Im could be a god and Joyboy / Nika back in the day could've just been some really normal looking people.
So here we go: Gods, Destiny and Ghosts. Three things people still don't wanna see in One Piece, Oda already did it before One Piece started and said he loved those stories.
Luffy is 100% a child of destiny.