Copyright was a legal construct the printers (not the writers!) lobbied for in order to increase their profits
I know how the "copyright" equivalent was created in the late 1700s in France. Beaumarchais was tired of printers and publishers ripping him off. He created the "author's right" (which is slightly different from the copyright US and UK countries use) to be protected against publishers and printers who would sell his work without giving him a cut of the profits. When it came to public execution of his plays however, he had no problem, because he felt a play should be... well, played, and that it somehow belongs to the public.
Later on, this right given to authors to control how they want their work to be distributed became more and more distorted.
All constants are variables.