ETA clarity to my post. What color is the last picture? That looks good. I think if you live with it like was suggested above you will like it. Accessorizing with some amazing colors for that wall color will help to pull the room together. I have a bathroom that I used BM Bunny Gray in and it looks like a baby blue. I have white, gray, and marble in that room. I have another room with carrara marble in, and I used BM Horizon, but that has a bit of green in it. The Horizon is very pale and might seem white to some. But the warming of the blue goes with my walnut. The Bunny Gray is a bit richer and looks fine with my whites, blacks, and marble. I tried many many samples for the marble in this room and settled on the Bunny Gray. No pink or green that I see in the Bunny Gray. This is a deco that I found and based my BM Bunny Blue room colors on. The lichen might have faded but the reddish in the mussles go well with the blue. The blue is very pale in these picture. click on them to get them full sized:

Okay maybe I’ll go back to original color (creamy). The walls were white before, but it felt very plain to me. Can I use a chandelier or pendant if there’s a shower in there? There’s not enough room for sconces ...

i would pull a color from your tile. on my monitor it looks like it has green in it. then hang a big pic of a tree or something in nature... your bathroom reminds me of 'bringing the outdoors in'.... while the wall paper is beautiful, your tile has so much movement in it, i would hesitate to do a busy wallpaper. simple is better here,

I would go all white and then change the shower curtain, art and other accessories to suite them as they grow and change. Let the 5 y.o. help pick out the shower curtain and then build the other accessory colors around what is in the curtain. Cheap frames around the mirror and art can be repainted as their color choices change with a new shower curtain every few years when they tire of the current theme. Here's a link to unicorn art and an art kit that might do wonders for you. https://www.houzz.com/products/query/unicorn-art