“Me” is Greg Gaines. He’s telling a story about himself, his psuedo-best friend Earl, and a girl he hadn’t been friends with in a long time who was forced back into his life, and who just happened to be dying. The characters in this story are full of snark, and (some more than others) what I fondly refer to as “rude boy stuff.” He’s an interesting character in that he goes out of his way to remain unnoticed by anyone.
Greg, through the course of the novel, purports not to learn anything from developing a friendship with a dying girl, and film making, and his pseudo-friendship with Earl. I suppose that’s something you’ll have to decide for yourself.