According to section 102 of Title 17 copyright protection does not extend to ideas, procedures, processes, systems, methods of operation, concepts, principles, or discoveries, regardless of the form in which they are described, explained, illustrated, or embodied.
In other words facts, ideas and slogans cannot be copyrighted; only the expression of ideas. A live performance such as a lecture or a sermon or a concert cannot be copyrighted. The video tape or audio tape of the concert is copyrighted as is a transcript of a lecture or sermon.
The quality of a work, its aesthetics, similarity to another work and even the amount of effort (or lack thereof) put into creating a work is irrelevant to copyright protection. Copyright rewards originality, not effort.
A good example of similarity is the oft told tale of forbidden love. It has been retold over and over again in a variety of scenarios as in Romeo & Juliet vis-à-vis West Side Story. The theme is not copyrightable but the details reinvented with each new telling are.
A good example of effort viz a viz creativity is a telephone book. A telephone book takes a great deal of effort to create but cannot be copyrighted because it is only a list of facts - names, addresses and phone numers. On the other hand a subject arrangement of those same facts are copyrighted because there exists some creativity -- minute though it may be -- in the development of a subject listing of names, address and phone numbers.