The proliferation of copies economically devalues the originals.
Behind a system of rights there is always a philosophy, which either postulates rights, or certain primary rights, as being somehow inherent or "inalienable", or else somehow justifies the establishment of rights without circular reasoning ("we need these rights so we can have nice things").
This is true. (It's true in every other industry as well.)
But the opposite side of that coin is that if you want people to spend the considerable amounts of time and money required to create new works that are actually any good then you need to have some viable model for compensating them that makes it worthwhile for them to do that. Whatever else you can say for it - copyright has been far more effective than any other model ever tried at the scale of human society in achieving that.
It's true that copyright makes a few people very rich. Some of those people certainly are artists. The "almost nothing" that Beyoncé has made from her music career reportedly paid for the private jet she bought Jay-Z as a gift a few years ago for example. Taylor Swift is reportedly now a multibillionaire. There's a reasonable argument that big name musicians have often worked on very successful concert tours and so not all of their income has necessarily required copyright. That argument doesn't really work when you look at bestselling authors or A-list TV and movie stars whose copyright-backed residuals and royalties keep them very well funded though.
Of course many of the other parties who make a lot of money from copyright are intermediaries like book publishers and record labels. The value of their contributions is increasingly questionable in the modern world and the measures they have taken to protect their revenue streams have sometimes been similarly questionable. I won't be sympathetic if copyright reforms render their business models obsolete and shift power back into the hands of the people doing the actual creative work with those providing services like distribution and advertising becoming subservient rather than the other way around as has often been the case historically.
Intellectual property creates compensation without a corresponding benefit to the public.
Edit: to add to this, the existence of copyright today does not show it has been effective for creating innovation. You need a counterfactual for that, which you did not provide.
That argument works if you're talking about something like a patronage model where most or all of the compensation for the creative activity comes from a single source. But it makes no sense at all for creative work that has a small value to each consumer in a large market. Copyright allows the cost of production to be amortised over a large market.
Intellectual property creates compensation without a corresponding benefit to the public.
No - because numerous members of the public benefit multiple times every day from the amortisation effect I described above.
You need a counterfactual for that, which you did not provide.
I'm not sure I really do. We can see clearly how finances flow in creative industries supported by copyright work. We can see the scale of both individual works and the cumulative production supported by copyright. And it doesn't take great insight to see that if everyone were allowed to copy and redistribute any work as soon as they had access to it then the whole model would collapse - again for the same reasons as above.
In any case if you'd like counterfactuals then I'll cite pre-copyright history, community-driven initiatives like FOSS and Creative Commons, and artists who have offered their work on a "pay what you think it's worth" basis. In each of those cases there have been some excellent works produced and enjoyed by many people - and the number of those excellent works is barely noise compared to the scale of production in modern creative industries supported by copyright.