In a story full of one-dimensional characters, Ginny Weasley is definitely the blandest of them all. No personality, no agency, no salient traits whatsoever. She's basically the princess Harry earns for being the hero, one of the many problematic lessons in J.K. Rowling's oeuvre.
I guess the teddy bear is the most extreme form of the foil, that supporting character whose main purpose is to show how heroic the protagonist is.