Yes I think a lot of people were having that problem. I did a pretty bad job explaining this in the game. You are supposed to wait for the "hero" to finish his attack. Then for a short period of time the "hero" leaves himself open to attack. If you then hit the "hero" with the attack that is weak to the attack he just finished, he will quickly dodge out of the way and counterattack which hurts the player. To make it so that you can not just run into the "hero's" attacks to kill yourself, there is a system where you automatically dodge most of the attacks from the "hero".
I think the fact that you can easily hut the "hero" by attacking him anytime, not just right after he attacks, makes it even more confusing to the player that they can't be hurt by normal attacks from the "hero". The Idea was supposed to be that the "hero" was a lot weaker than the boss/player so it is actually challenging to lose the fight.
Just writing this out though I definitely see how confusing the idea is haha, but oh well next time I need to make sure to more clearly explain the game mechanics.