How is Amir the true hero rather than Hassan in The Kite Runner?

The protagonist of Khaled Hosseini's novel, The
Kite Runner, Amir makes up for his earlier transgressions when he returns to
Afghanistan to rescue Hassan's son from the Taliban. Amir had acted cowardly in his
previous treatment of Hassan (refusing to help him while being raped and planting
incriminating evidence against him); however, his guilt over these transgressions
haunted him continuously as an adult. When Amir learns that Hassan is actually his
half-brother, and that Hassan's son, Sohrab (Amir's half-nephew) has been left behind in
Afghanistan, he realizes that by rescuing the boy and returning him to America he will
make amends for his earlier faults. He risks his life by just re-entering the
Taliban-held territory and barely comes out alive when he frees Sohrab. These actions
could certainly be called heroic, though I doubt that Amir would have considered them
so.