Why does campfire lighting look creepy?
There are situations as you mentioned where light can be from below, but they are extremely rare in our evolutionary past. Fire is quite recent: remove that one. Reflections from water or snow would require very strong light from above, so those are essentially removed as well. I think the creepiness comes from the unfamiliarity. Also see the Uncanny Valley, which describes similar feelings in response to near-human representations https://en.wikipedia.org/wiki/Uncanny_valley

A good test would be with non-human animals. Do they find bottom-lit faces fear-inducing?