Good observation on the theme! I actually started this just to make Breakout, but I decided to create art halfway through and it eventually morphed into the final version. I wish I'd have come up with the theme in the first place, I could've tried to have it make sense.
The bouncing horizontally is annoying. But what is worse is the bug it replaced. If you hit far enough to the side, the ball's direction would go down instead, straight through the paddle and into the void! I should have tightened the angle possibilities to prevent the super-boring wall-to-wall bounce problem, but I ran out of energy. My wife hates when it does that too, that should have clued me in earlier.
As for the music, I grabbed a track off a random midi generator last minute and it sounded nice enough. I wish I'd got some happy bouncing music, or at least something a little more uplifting. I do love pirates, though - maybe it's just unconscious bias...
Anyway, thanks for playing and leaving such detailed feedback! I had a lot of fun making this, and I'm proud now to tell people "I made a game!" I just don't elaborate on how original or well-designed it is :)