Is Holden a static or dynamic character?

Holden Caulfield in my eyes is a dynamic character becacause at the begging of the book all Holden wanted to do was be the catcher in the rye because he wanted to help people keep their innocence by keeping them sheltered form all the bad things in life. But at the very end of the book Holden starts to break down while walking in the park and relize that no matter what he does with all of his power and might he can not be the catcher in the rye. No matter how hard he works and tries he can not save anyone from anything he is just one person against the world. At the end of the book Holden finds F.U. written on the wall that all the kids can see including his little sister Phoebe. Holden just get's really angry at first because he thinks the word is taking away from their innocence but then he says "If you had a million years to do it in, you couldn't rub out half the F.U. signs in  the world". Holden is a dynamic character because he changes as the book goes on and very drastically for that matter.