It’s not boilerplate. If you want to argue semantics that is the heart of the conversation. If we can’t agree on how things are defined then we cannot begin discussion on specific definitions. Languages evolve over time and if we aren’t in agreement about that then there is no point in debating semantics.

To the point in your second paragraph, I would argue that we attach humane to a subset of characteristics that we view as desirable for a human to have and inhumane as undesirable characteristics for a human to have. The words have nothing to do with what characteristics actually do belong to humans. It is nonsensical to even talk about a subset of characteristics that belong to humanity as a whole since every individual is different and can display various characteristics. You can also view it from the lens of inhumane being another way of saying “your actions are so reprehensible that I have a hard time viewing you as a human”. We hold ourselves to a higher standard than the rest of the animal kingdom because of our ability to reason. We have a higher moral agency. If you do something like murder and you know it is wrong you aren’t acting in a way that strives towards the ideal of what being a human is that we have created as a society. By calling that person or their actions inhumane you aren’t literally saying that they aren’t a human or that a human can’t perform those actions. Obviously they are and they can. I have literally never heard anyone try to argue that the word “humane” means or should mean the same thing as “human” and “inhumane” means or should mean the same thing as “not human”.