Because the song is an original work, its copyright belongs to the creator and is protected by law. Other singers need the authorization of the creator to cover and publish, otherwise it will be regarded as infringement.
Copyright, also known as "copyright", is a legal term used to express the rights enjoyed by creators because of their literary and artistic works. Simply understood, copyright refers to the legal ownership of the author's right to copy his created photos, movies, computer programs, literary works, music and other works.