The current animations are fine in my opinion.
They may be simple, but they have their own style which compliment Blockland as a whole.
And because of their simplicity, they are quick to activate and not to forget, process.
Maybe the crawling animation could be revised, it is just wiggling the player in a flat position.
A couple of new animations in the same style could be implemented.
I was thinking of a sprint animation: leaning forward, faster leg movement, little bit of jump in between steps and leaning to the sides in corners.
Other than that, I don't really know what should be added.