Would you mind sharing a video of you playing the game? Just to make sure you are not facing a bug.
Or maybe difficulty does need to be optimized. After all we have been practicing the game for a month and can't really judge it fairly. But seeing someone else play it will help greatly.
That said try the very first rat. Its rhythm pattern is the simplest and 1000hp should let you practice the game. If you missed the stick item, it is in the crime scene near the start of the game.