I must be misreading this. Are you saying the following is/should be okay/ethically okay/perfectly legal:
Author A spends a year writing a fiction book. They are not well known in the industry. They publish the book, it sells very few copies (perhaps none at all).
Person B (a well known Instagram influencer with tens of thousands of followers) downloads a copy of your book. Replaces your name with their name as the author, and promotes it as a book they've finished writing. Goes on to sell at a very profitable rate.
If your answer is NO this should be illegal, what about if Person B searches/replaces all definite articles with indefinite articles, or changes all the proper nouns to begin with "schmla"? Where do we draw the line?
If your answer is YES, then my gut instinct tells me you are neither a writer, composer, or creator in any meaningful sense of the word.
I wrote a fiction book, which has sold virtually nothing (maybe $50 gross, against an out-of-pocket cost of ~$4k). Both of these would piss me off if they happened to me or my author friends; I also don't think they should be illegal.
I am an author, a digital artist, a programmer, and an extremely amateur musician. None of those things have demonstrated to me why copyright law is necessary, a net positive for the world, or ethical.
Why? You are holding a belief that works directly against your own self interest.
If it's a principles thing—I'd ask, what is good in this principle? What is the good in someone else taking credit for your work? What is the good in someone else divesting you of wages you could use to live or support further creative acts? What is the good in any of that whatsoever? What real harm is the protection afforded you by the IP causing? If you worry underprivileged people can't access your work, you can give it to them for free as the IP holder. I simply cannot fathom any reasonable abstract position in which not having IP would be good for you. Sure, if you hand over your IP to someone else, I could see wanting IP abolished, but that's on you. Thant's the same as the parent scenario only you actually got a say in the matter at least.
Yes, I think it is okay.
I think a very interesting case study would be YouTube. This exact scenario happens there regularly, with various consequences for the creators.