The “forbidden sun” got me thinking, what exactly could humanity by desire touch that would ruin the world like this?
And the way the world was destroyed darkness and fire made me think of a quote from Lord of the rings, and it made me realize there’s a possibility that the forbidden sun is the earths core.
As Saruman Said: “Moria. You fear to go into those mines. The dwarves delved too greedily and too deep. You know what they awoke in the darkness of Khazad-dum… shadow and flame!”
Perhaps this is something similar to what occurred here in the first world. The humans out of their greed and desire began to use the earths core itself as a power system, and maybe what powered the ancient kingdom in general.
The “Dig too Deep” trope sure as hell ain’t a new one and Oda is very likely aware of it because of one of japans most beloved Kaiju, Radon. The Flying Kaiju of fire who awoke because of this exact trope. (And I’m pretty sure at this point a lot of Kaiju were retconned to have been hatched/awoken due to mining).
So perhaps that’s what really started all this off, humanity greedily deciding to mine the core of the earth itself causing the awakening of these two monsters that ended the first world.