I actually think this is looking great, unless there's a good reason to introduce more colours it works really well as is, especially when I "pan" it using my hands. The use of only a couple of colours reminds me of
this piece by Helm which I always liked cause it didn't try to use the whole palette.
The rim lighting on the characters is maybe a bit much in places, mainly on the staff and around where the character meets the tree, I would say either get rid of it on the tree or pull the character to the left a bit, you're confusing the depth. If you're going with the brown light maybe consider throwing that up on the tree and maybe even as a secondary light source on the characters. The perspective is a bit wonky but you can get away with a lot with a panning camera so I wouldn't worry about it too much.
