I love how you interpreted the theme!
In the Intro, it's really cool how you used (at least how I interpret it) the guitar and the piano to represent each brother.
In the second track, I can imagine the old man trying to remember a song pretty well, mainly because of the pauses between the notes and because he only plays one note at a time.
The tutorial fits well as a tutorial and because there are mainly scales and o big intervalls, I can imagine a child playing it.
Together with the intro, the last track is my favourite, just because of the simple but beautiful melody.
Over all, you really nailed it. There's nothing too complicated, but the soundrack just fits the story soooo well! Keep going^^