"Original" songs take melodies or something else from songs that are already made, remix them, and claim them as their own. This type of thing also happends in movies. The same type of movies will usually have the same plot line. Take, for example, Disney princess movies. A girl does something to rebel her normal life, meets a boy, falls in love, a complication arrises that separates them, they meet again, and they all live happily ever after. Sound familiar? That's because that plot has been used in most, if not all, of the disney princess movies, or even just fairytales in general.
For something to actually be original is nearly impossible since so many little things and tampered with to create that "original" idea. This is not a bad thing, though. It causes for people to be able to move forward in technologies and innovations. The idea of remixing is what pushes mankind forward in life.
-Post by Kathleen