I think it's a fun little concept,
I think if I were to improve upon a few things they would be these:
1. Collisions, the current ones are extremely...imprecise and that makes it a bit frustrating to judge stuff
2. I think the actual growing of the square could be centered, this way, there's a better perspective on how you're growing, rather than growing towards one side
3. I think the art could honestly be more simple, just black/white, with simple outlines for things, and that would really make the game pop more visually
Otherwise, a great proof of concept for a beginner game, keep it up!