Personally, I'm kind of imagining Imu as being something like Judge Doom from Roger Rabbit.
Imu as the last "pure" human left on the planet. The only one who hasn't been hybridized with any of the other races of the One Piece World. The only human who hasn't been affected by the "terraforming" or "alteration" of the World.
We're starting to learn that this World has been alterned in some way from how it was originally. With "Continent-Pullers" and environment reshaping Logias and the whole world flooding. It's just a matter of how much. And I'm personally betting that this World has been altered a LOT! I think Oda could use this "terraforming" to explain why the One Piece World's characters look as "cartoony" as they do.
A hyper-realistic, "normal" human living in a world full of "toons". But, who might be "infected" by the "tooniness" of this World by the Devil Fruits.
https://editorani.wordpress.com/202...ers-of-evil-is-a-harsh-reminder-to-real-life/
(Flowers of Evil, with it's "rotoscoped" style)
I don't know. I just think it'd be interesting if Oda used a completely different art style while drawing Imu. Just to make Imu seem all the more "alien" and like they don't belong in this world.
...There's absolutely NO basis for any of this, though. I just think it's a fun idea. But, it MIGHT explain why Imu hides their appearance from everyone. To everyone else on this world, they would look like a freak of nature. Even though, Imu just looks like what humanity used to look like before they "mutated" to survive on this World that they've altered.
There is a alternative that I've been kicking around in my head, too, though.
I think people are starting to come around to the idea that Imu could have some sort of Dragon Devil Fruit. I think that's making more and more sense to some people.
But, what if we have it reversed?
What if Imu isn't a Human who ate a Dragon Devil Fruit? What if Imu is actually a Dragon who ate a Human Devil Fruit?
I know that might seem like functionally the same thing, but it'd actually be kind of a big reveal. As far as we know, Ryuma killed all the actual Dragons hundreds of years ago. Imu might be the last of their kind.
And we know there are different models of Devil Fruits. Chopper might have the "vanilla" Human Fruit. But, maybe Imu could have another model of "Human" Fruit. This would make a lot of sense if Imu ate one of the God Fruits, which ARE "Human"-type Fruits, technically (I'm betting on "Forest God" specifically.). Chopper does have a "X" on his hat. And as we all know "X marks the spot". Chopper might have been foreshadowing something like this happening, all along.
And it might actually explain some of Imu's actions during the face off with Sabo and Cobra. Imu didn't turn into a Dragon to fight Sabo. Imu was enraged or hurt by what Sabo said and lost control, reverting back to their "base" form. Maybe Imu has to focus to stay in "human" form. But, when they lose control of their emotions, they revert back to their "original" form. That would kind of put some of their actions in a new light, which Oda does love to do.
Again, no basis for any of this. But, it's another idea to put out there. It's something to think about.
I'm not sure which idea I actually like better, honestly.