Hope it's ok saying this out here, but I think in terms of making the thumbnail even more appealing, you could try removing the rock in the bottom-middle. It's quite alike the rock in the bottom-right, but does not find repetition in the image elsewhere. It's a little distracting and blocking the path towards the character. Just putting a thought out there, not sure if it would work
Using straight lines means much in this context.
think that's what these communities are made for - and you're absolutely right, so thanks for being honest, I appreciate that very much!