Protection under the copyright law (title 17 of the U.S. Code, section 102) extends only to original works of authorship that are fixed in a tangible form (a copy). “Original” means merely that the author produced the work by his own intellectual effort, as distinguished from copying an existing work. Copyright protection may extend to a descripttion, explanation, or illustration, assuming that the requirements of the copyright law are met.

https://www.lawweb.in/2012/09/what-can-not-be-copyrighted.html