First person allows deeper insight into the protagonist's character. It allows the reader to identify more fully with the protagonist and to share her world quite intimately. So it suits a story focused on one character's personal journey. However, first person shuts out insights into other characters.
Juliet MarillierA wonder tale can be truer than true," I said. I had learned (...) that the deepest kind of truth can be found in the strangest and wildest of stories. One may not meet a fire-breathing dragon on the way to the well. One may not encounter an army of toothed snakes in the woodshed. That does not make the wisdom in those tales any less real.
Juliet Marillier