Triangulate the rays in these images and it appears the sun is just a few hundred feet away.
Possibly, likely probably, might be so in fact, that as light crosses so-to-say biome borders, then that border area or "gate" area acts as if true source for that light, and sort of makes light spread again. Similar to how tree branches branch out ever more. And so actual true sun, whatever it is, could perhaps be behind many different layers of worldly elemental or biomic levels, each taking what is suitable to theirs and rest of light passing onward to lower or thicker levels. Which hints at "Earth's" size... very very big. Modern map of Earth being only some tiny bit of whole.
Each layer or level also having their own so-to-say base color or tone, and source of light having something to do with "DNA" of this world... Meaning various qualities and aspects that translate into various colors and tones and qualities of light.
And lots more to this angle of approach, to trying to figure things out.
Certainly not flat... And concave alone is not enough, but is a good "beginning point" to begin figuring out. Because inside not outside, and if outside then that outside is in far bigger inside.
Our world as whole, not only this "Earth map" area, is one massive living being. Or perhaps was in case someone high up died long ago, and parasites and such began infesting resulting rotting body that is rather far beyond modern understanding god level.