I can see that the art is the emphasis- it's very cute, and honestly probably too nice for this jam. There's definitely some weirdness to the physics. I've had the ball/heart non-intuitively bounce back, and I had to restart because it got stuck on the bottom twice in the first level. It gets more tedious and annoying as you get closer to the end of the level, but that's hardly unique to this game, most Breakout clones are like that. The later levels are more interesting than the first, and I got to the third before game over.
I usually use opengameart for music (and sometimes other assets) and freesound for sound effects.