thought continuing onward

The problem is with story - conveying this kind of emotional arc via animation might end up looking more like an animation exercise rather than a short, which is the intention. Especially true because of the complexity of the rigging and compositing.

I need the character to have a goal (problem). Maybe wants to get something, but it needs to fit within the reality of a hodgepodge character. Don't want to anthropormophize him - what exactly would a 2D character who finds himself in a 3D world need/want?

Since I already have a second character, possibly
have him interact with the first in some way, and have that be the story.

Above all, it shouldn't be philosophical masterbation. If I do that, it should be an essay, not animation. Keep in mind that first and foremost that this needs to be a story that can only be told in this medium - can't be done in live action, can't be done in writing.