Hey there,
Your tiles are really solid in terms of the palette and how you are applying pixels, but the set seems overly detailed, and the forms are flattened due to bringing up all the details to nearly full highlights. This makes the rocks look overly busy, and more "noisy" than something as solid and planar as rocks.
I made an edit; the effect could be taken even further, but the point is to round out the forms more and obliterate some of the detail for a larger, more gradual fall of gradient light. I know some bits will be difficult as this is a tile set made to link different pieces together, but I found myself editing same/ similar clusters to similar levels, so I think it can be done.
This takes into account more of the whole picture, the gestalt, which can be harder to grasp in tiles which by their very nature separate things. Attention to these larger concerns can help guide the players eye and allow them to properly focus on the walkable parts of the cave