Copyright does not protect ideas, just specific expressions of ideas. So even if something sounds like a derivative work, it doesn't mean it's infringing. You can write stories about a fictional 19th century detective living on Boulanger Street in London without infringing on Sherlock Holmes. You can write reviews of Disney movies without Disney's permission.
AI does not understand what ideas are. AI does not think. It just takes source material and regurgitates it.