There're two details I noticed while watching the movie that are just way too cool to not talk about, aiding the narration of The Kid and the ending.
1, in one of the flashback scenes, his mother held his hands and gently map out the root lines inside his palms and told him that these lines tell a human's future. We learned that Monkey Man's hands are burnt trying to save his mom, he no longer has visible root lines. His future died alongside his mother.
2, aiding to the bit above, another flashback screen has his mother asked him what would he like to be when he grow up. We saw him answering, but we never heard or made it out what he wanted himself to be when he's grown.
Just. Beautiful and heartbreaking scenes + symbolism.