The issues you mentioned are indeed errors occurring in our game, and we deeply appreciate you bringing them to our attention, as this helps us make significant improvements for future development. You are spot on—the problems most likely stem from the zombie hitboxes. It is also probable that these issues arose because, at some point during development, we had to rescale the entire environment; the zombie and player sprites had already been implemented at a specific scale, and failing to account for this from the start was a mistake. Consequently, there may be errors with the colliders in the Animator or the prefabs.
We will also take the UI into account; we know it is a fundamental factor in the user experience. Since our game is a side-scroller and quite long, you are right that players might forget the controls. We will keep this in mind for future development.
Best regards, Tsukuyom.