I agree with much of what you're saying... we stand on the shoulders of giants... in all fields.
That said there's a difference between writing something old in a new and better way and the whole cloth theft of a fictional character created by another writer . It crosses some kind of line with me... But yeah - in many cases when it's done it's done better. Often worse...
Years ago a friend who was teaching writing told me there are only 7 themes for novels ... should have asked her what she thought they were...