under-stand
de-pressed
up-lifting
The real question is why is up good and down bad, i.e. why is heaven above and hell below.
Discussion
Think you answered your own question 😁
I did not. Why is "the under-world" universal and bad? And don't say lobsters. I dare you. 
cultural memory of lava coming from the ground?
Could it be linked with and perpetuated by religion? Anyway, probably just humans being scared of the dark because they can’t see.
well, i think some of them resemble insects, but mostly humanoid
every culture has stories about them and the modern format is the "aliens"
the bible calls them Watchers and Fallen Angels, the irish call them Aes Dana, every culture on the planet has stories... when you look at south america, the "food of the gods" - theobroma - cacao - according to the stories of those people, they had big, somewhat elongated heads, pale skin, and demanded human sacrifices, there is traces of them everywhere, they built pyramids etc
fair and white, also...
his story
It's interesting that it's cross cultural, in Chinese hell is something like "underground prison" and heaven is "sky hall" or "hall in the sky"
Is this not something to do with light and dark? Our light source is above us and the darkness is below us? And then biologically/physically would you prefer to be at the bottom of a deep pit or on top of a mountain? Is it not safer up high?
Because as self-replicating material entities, for us, "more" fundamentally equates "better". And it is.