The overall idea of what happened 800 years ago:
To make it easy, I will share this previous theory of mine, it's about mihawk lineage but it give an overall idea of the number 16 and what is the inspiration for world government:
The order of the defeated dragon is called like this because they fought and defeated the dragon. In one piece these dragons would be the celestial dragons and the order the WG. We all know Oda is a big fan of star wars so basically WG=jedi and celestial dragons=sith.
To back up this claim I found an interesting chapter in 16 (chapter in 16 are supposed to be WG and imu lore whether it's disguised or not) it's the chapter 970 (9+0+7=16) Oden Vs Kaido:
I think we all know what happens during this chapter
Yes the WG slayed the dragon but just after that got fooled (by Imu) which let the dragon have a decisive blow on the WG.
But what led Imu or should I say Anakin to betray the WG?
It turns out the meme about Imu being a cuck is really not so far from the truth. There is a chapter in 16 which could look trivial at first, but is quite interesting, this chapter is the chapter 916 (9+1+6=16) Wano sumo:
In this chapter a sumo get rejected by okiku and decide to kill her but Luffy save her. So basically Imu (Anakin) attacked Lily (Padme) and Joyboy protected her.
Who was joyboy?
Now we re really entering the shady territory, I don't have any chapter to back it up but basically, the order of the defeated dragons were noble who associated themselves against Türkiye (not really sure of that but it doesn't really matter). The thing is they were not 20 founding members like what we know in one piece but 21, so joyboy could be the head of this lost family.
The WG was founded by the D, which would explain why Lily is one and they fought the celestial dragons but ultimately lost because of Imu betrayal. The truth got turned upside down during the void century and the D became the bad guys.
So this would make Imu a D and could explain why rocks and Blackbeard are the way they are.
I also think that the red line which is basically ouroboros or Jörmungandr should I say, was a real giant dragon which got defeated by the ancient weapons.
It would explain why Shiraoshi is Poseidon.
Also broggy and dorry made a reference to Jörmungandr (they called him the blood snake which is one of his name), they said that only the blood snake skin could resist their attacks which could imply giants actually try to attack red line at some point in history.
So what do y all think of the theory?