The camera is way too close for the level design. Many of the jump are just blind jumps that you hope for the best not to be a death pit or an enemy you can't jump on.
Additionally, the game should be able to let you select each level instead of starting at the beginning of an entire world.
Also pretty sure it's complete RNG whether or not you get hit in 3-3 since those balls will almost never be in a pattern that can crossed without damage boosting.