I believe the actual law is the clearest answer to your question: US copyright law, Subject matter of copyright 102.(b) "In no case does copyright protection f

I believe the actual law is the clearest answer to your question: US copyright law, Subject matter of copyright 102.(b) "In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work." (https://www.copyright.gov/title17/92chap1.html https://www.copyright.gov/title17/92chap1.html) Quite explicitly, copyright law doesn't grant the author any exclusive rights to the ideas expressed in the work, just on the particular creative expression.