Talking about Friedrich

I think that Friedrich would be the most important, (that is, along with the narrator in a way as he is the one telling the story) since:
1)The book's title is 'Friedrich'
2)He is the 'main character'
3)He is, in a way, representing the Jews (other than his family) and talks about/shows what happens to them(in the sense that the things that affected all Jews during that time affected him along with his family).
(BUT I really think that the narrator's just as important)