You could go any number of ways with paint color. A removable wallpaper might also be fun.

Personally, I think I might just keep it simple, keep current paint, and simply bring in a new shower curtain, maybe just a plain white liner, and some art.

These are all available on Etsy.com.

I think with a new shower curtain and different art, this room would be transformed.

If you wanted a more artsy/whimsical type of shower curtain, I think something like this could also be fun - if you like cats.

https://www.amazon.com/gp/product/B07JC7BM28/ref=ox_sc_act_image_9?smid=A1V80NX2C2TWHI&th=1

Its a nice color, and pretty much on trend right now. However, I agree, with you. I would be repainting it too. You could go white and then use bold color accessories, or you could go with a pretty aqua, or blue, with all new accessories. Pick your favorite color and then go from there. The room is neutral enough that you can use most any color you choose. The painting on the wall is pretty, but, I dont see any of those colors carried over into other accessories, so thats also a possibility. I would like to see a bit brighter happier looking space though.

Pick a new shower curtain and then chose paint color from it. Everything is neutral so pretty much any color will work