Makes sense to say that monsters are inherently evil, yes. If I understand, you are raising the question of whether we should say that actions are evil but people are not. My thoughts are that evil isn't a force or entity (there's no devil) but that evil is a free will choice, so a person can choose to do evil just as they can choose to do good. Because who we are as people is constructed by our beliefs, choices, and actions, a person can in a real sense become evil. They can sill choose a different path so they aren't evil essentially. We can condemn actions and people who commit them.