Just as a quick note, I don’t think I have sufficient information to conclude that the race of the Ancient Kingdom were devils, however, I think there’s a lot of small and big hints that heavily suggests that devils will make an appearance.
Some points before I start my theory:
- The “Family of D” were known to be the Natural Enemy of the Gods.
- The country Rosinante grew up in told stories about how misbehaving children would be eaten up by the “D”s, which kind of reminds me of stories used to demonize certain native populations that were mistreated throughout history.
- The devil fruits are unexplained, and already have the name devil in them, which is odd, given that there is no such race confirmed to exist.
- In chapter 183, Usopp said about the dog gun of Mr. 4: “Bullshit! How can it move if it it’s a gun? Devil fruits don’t have a mind of their own!” As we all know, Usopp is a living spoiler with his lies. Maybe this is a sentence Oda used to hint that yes, devil fruits do have a mind of their own. Awfully convenient that this is how Usopp the living spoiler reacts to the first mention of the “new technology” where even inanimate objects can eat devil fruits.
- Xenophobia seems to be the main evil selling point for the Celestial Dragons. They think themselves above everyone else, to the point where they won’t even breathe the same air as the general human population.
- Kaido, Black Maria and even Yamato and the skull in which they live in, all seem to have similarities with their horns, and Oars and Oars. Jr additionally have huge teeth. While they are currently classified as giants, I wouldn’t be surprised if they were actually half devil.
- If devil fruits actually contain the souls of devils, it makes more sense why their users would interact with haki the way they do.
Okay, so you probably already got the gist of my theory here while I was typing out my points, but basically, I think the Ancient Kingdom, Devil Fruits, the “D”s and Joyboy all have something in common: They have devils in them. Haha, yeah no, I’m not kidding.
I think the Ancient Kingdom was actually a country of a race that up until this point has gone under the radar, and for good reason. This race is called “devils”. Basically, my theory is that devils were one of, if not the first inhabitants of the One Piece planet. The “Gods”, humans, descended from the heavens and laid claim to the place. Wars ensued over natural resources. The humans had superior technology and weapons, but devils had weird abilities to turn into all kinds of animals, the elements and lots of other weird stuff, that made defeating them really hard.
The humans, with their military and scientific knowledge, built the ship Pluton, and with it, they got the upper hand in the war. However, the devils had their own allies: A fishman queen, wife of Poseidon, and they fought back with the help of the largest creatures of the oceans. That’s when the final superweapon was built, Uranus, and with it, the humans controlled the weather patterns of all the seas, creating the Grand Line and banishing all the Sea Kings to the Calm Belt, bending the entire planet to its knees. They then used Pluton to commit the greatest atrocity imaginable, they put all the devils on their homeland, and blew it away with a single shot.
Some devils survived however, scattered, hunted for being themselves. They allied with the samurai of Wano and the minks, and chose to inscribe their story of what happened to them to future generations. Maybe the devils were hunted down and killed after that, or maybe they chose to intermarry with other species, and carry on the will of the devils through them.