How does humor assist Arnold (Junior) in creating his own identity to be a "full-blooded Indian" in The Absolutely True Diary of a Part-time Indian?

From the beginning of the novel, Junior uses humor to
introduce himself to the reader.  He draws pictures of himself that exaggerate his
physical disabilities and oddities, and these self-parodies allow Junior to express
himself.  Throughout the story, Junior tries to take the hardships that he experiences
in stride, and often he resorts to humor to deal with the harsh realities of life on the
reservation.  When Junior gets into serious arguments with his best friend Rowdy over
Junior's leaving the rez to attend school at Reardon, Junior draws cartoons to
illustrate their conflict.  In the end, Junior learns that even though there are harsh
realities on the rez, there is a sense of beauty and community there as well.  He and
Rowdy are able to rekindle their friendship, and this suggests that Junior has accepted
his full-blood Indian identity.