Specifically though, if you decide to record Beethoven's Fifth, which I believe is in the public domain, YOU get a 50 year copyright on your performance of it. Whatever unique aspects of it you added, whatever nuance, that's yours, and belongs to you, licensable, sellable only by you, for the period of 50 years. Nobody else can duplicate your performance exactly, unless in doing so, they are also duplicating the original performance exactly.
Specifically though, if you decide to record Beethoven's Fifth, which I believe is in the public domain, YOU get a 50 year copyright on your performance of it. Whatever unique aspects of it you added, whatever nuance, that's yours, and belongs to you, licensable, sellable only by you, for the period of 50 years. Nobody else can duplicate your performance exactly, unless in doing so, they are also duplicating the original performance exactly.