The concept of scaling up and down a ball is quite good: it’s simple and could lead to pretty cool gameplay if exploited correctly. But I think it isn’t in “Ball!?”. The game is way too easy and feels like a puzzle-platformer even though it’s not. If I were you, I would either completely go down the route of shaping it into a puzzle game, or I’d focus uniquely on the changing the ball’s size and jumping mechanics to make it another genre. For exemple it could easily be reworked to be a geometry dash-like game where you die when touching the ceiling and the left side of the screen and need to get to the finish line. Before working on anything visuals-related, you should really focus on designing a primary gameplay loop that is exploits the scaling idea at it's full potential.
But just so you know, I’m just a hobbyist. I have no background in game design and you shouldn’t take my word as the ultimate truth. I’m only giving you my honest opinion on the game and some ideas on how to shape it into something (hopefully) better.
Have a nice and enriching development journey ^^