The answer is in the name of the law, copyright, the right to produce a copy. The original, ethical intent behind the law was to encourage people to create things. Someone could invest time and money into creating some art that had value, and then they were given the exclusive right to monetize it for some amount of time. You could create something, and I'm not allowed to copy what you created, and sell it without your permission, preventing me from doing no work but capturing all the money you could reasonably make off your work.
Want to create a song? You're the only person allowed to make, or authorize people to duplicate it. You're the only person allowed to control the supply of your effort. Eventually, the public good, and interest was supposed to take over, because in the end, you're right, it's just information. It was supposed to enter "the public domain" where anyone could freely use it. But then Disney got involved, and now it's a toxified weapon used mostly by unethical lawyers against curiosity.
