If you want to be that hyperbolic you could say that writing letters to make words is not an original invention. We're talking about major story elements here which play out across a ton of stories. I think that's derivative. You don't and you've made your point well. I guess I enjoy derivative work equally alongside original work. If Harry Potter is telling the same story as Star Wars it doesn't matter to me. Both were fun to watch though I prefer Star Wars.
I answered that question succinctly with Star Wars. You said that it was guarded from guilt of derivation under the protective category of the monomyth. I disagree with your argument as too broad and told you as much. If you'd like to have another try at explaining why stories which are as similar as Star Wars and Harry Potter are not derivative of the former as the former is derivative of many stories which came before it you are welcome to it, but your tone is rude and doesn't help you in any way.