I don't think copyright was intended as property as such, but since it can be bought and sold, it might as well be.
What galls me is that when the terms of copyrights were extended, they made that apply to unexpired rights granted for shorter terms. That is simply stealing from the public domain. The costs and risks to create such material were already assumed under the original terms, and most of the expected or hoped for rewards reaped. I don't find the "ownership rights" to such material legitimate at all.
I think the current term for copyright is something like the life of the author plus 70 years, or 95 years for corporate works. Nobody determines whether to invest money or effort on expected returns that far out. This is closer to a perpetuity than a limited time.