I know you are trolling but lets say oda introduced imu as a character from shandora 900 years ago with tokis fruit or some shit where we have no idea with how his powers currently, and he stated he is an ancient ruler or something and pluck him in this chapter
I would not bat an eye at believing that
I fail to see any characterization that he is not a regular guy with powers we dont fully understand just now.
Joyboy was a regular dude too, and he can do haki knots and probably other shit we dont know or yet is not explained
Honestly, you can say that Imu was introduced there to some point. Shandia fought an enemy. I think this was built up for WG as an enemy introduction. Again, the reason why Oda compared the final fight to the Marinford battle is that it will happen in the same place. Admirals were always planned as the main obstacle and main soldiers of WG, except Gorosei, of course. I mean, Oda drew Gandhi's sword before he showed WB. And it was clear that Gandhi had the Sandai Kitetsu sword. Which is supposed to be Zoro's final fight.
Imu and Whitebeard are foils for sure, they are opposites in many ways but their roles in the story are the exact same.
Whitebeard was known by all, he was called a Devil but in truth he was one man with one heart as he said. He was feared by all but at the end of the day he was a good man with one heart.
Oda wanted to show us how Luffy would fight against WB, and he made BB eat WB fruit for that reason only.
Imu is known by few, those that do know him call him “the true god” but he is more akin to an actual Devil. The WG is still trusted by most of the OP world but Imu (who represents the WG) is evil as shit
The problem is with Imu that he cannot be surpassed by BB in his Evil. Even Davy Jones was nothing in comparison to Imu. Why? Because Davy Clan, D. Clan was all about Freedom and death with a smile. Imu is the opposite of freedom. The fight for Raftel should happen only between pirates, because that
fight will show the real Heir of the D. clan, who will get a
right to defeat D. Clan's enemy - Nerona Imu. Again, this is a Dragon Ball scenario when Goku and Vegeta fight against each other, but in the end, only one of them got the
right to revenge for all the Saiyan race pain, and kill Freeza.
Imu is Freeza in One Piece. He is guilty of millions, or even billions, of deaths. Just mention of D. clan name makes him angry, and he will kill you on the spot. And he is the king of WG.
Who killed Roger? WG. Who killed Ace? WG. Who is guilty in Nami's situation? WG. Who destroyed Ohara? WG. Who required corrupted Warlords? WG. Whole One Piece was a buildup of the major war against the World Government.
I believe Imu was always in Oda's plan. Again, the World Government always represented the UN from our world, and the Gorosei - massons. But Masson's lounge religion always included Pyramid, so the secret leader was always there. Plus Bible 2 Corinthians 4:4 about the "god of this world".
Now the only thing that Imu lacks is the personal grudge against him from the SH. Which should be fixed in the Elbaf. This is something that Oda shouldn't fail, because if this were just a defeat overall, this wouldn't be enough to feel hatred from Luffy against Imu.
As for build up of fight against the World Goverment, it oficially started from Wapol Arc, where the meaning of the Pirate Flag was explaned: