When I was seven, we finished the basement to our home and my twin and I chose our paint colors for our own rooms. I chose pink for the walls and yellow for the trim. It was awesome!! ...for a while.
It's okay to keep things you love and that spark joy! I'm not actually downsizing for necessity, I'm simplifying my space. I love having full shelves of books. I simply needed to make sure the shelves were full of books that I enjoy and would like to read (again).