We’re all aware of what happened in the most recent string of chapters where Luffy’s Devil Fruit was revealed to be that of a Zoan, specifically Human Human Model: Nika, instead of the previously believed Paramecia Gomu Gomu.
This is the first time in the narrative we’ve ever had a Devil Fruit without a real world counterpart, mythological or otherwise. While many see this revelation as a definitive and maybe unnecessary payoff to Luffy’s Devil Fruit I think this is a deliberate discrepancy to set up for something else, namely the origin of Devil Fruits.
It’s been stated by the Gorosei that Zoans are the only class of Devil Fruit with a will of their own which makes a lot of sense when you remember every single inanimate object that has “consumed” a devil fruit has done so exclusively to a Zoan type. Since it’s implied people treat the entity named Nika as something independent of a Devil Fruit, it makes you wonder how (if at all) Nika was “converted” into a Devil Fruit.
Another thing I think worth mentioning is that one of the main focuses of the Yonko Saga has been the research of the Lineage Factor and how that ties into the how of Devil Fruits. For the uninitiated Lineage Factor is akin to DNA and is referred to in-universe as the Blueprints Of Life. The research has been used for the Vinsmoke children but more importantly for the creation of Artificial Devil Fruits all of which have been exclusively Zoan.
I think the Nika revelation and the entire Yonko saga has been subtly nudging us towards the question of what Devil Fruits truly are. Since we’ve established that there is no real world counter part to a Sun God named Nika this leaves us with one question “What came first the Nika or the Fruit?”.
And as a bonus, Blackbeard’s Devil Fruit is most probably secretly a Zoan as well. Not just because of the Sun and Dark parallels with Luffy but because in his fight with Ace he explicitly states his Devil Fruit chose him.
Theory by Optimus_LaughTale (https://www.reddit.com/user/Optimus_LaughTale)