And what if you both sit in a life drawing class drawing the same model? What if for some odd reason you decide to sit behind one of the participants and draw a portrait based off their drawing?

I certainly understand what you're getting at, but everything that we do today is based off of some idea that came before us. Is a certain level of indirection required for an expression to be considered appropriately unique?

From the article, "..there is a line between copying ideas and copying the original expression of ideas...", I would consider that opinion to be both myopic and absurd. We stand on the shoulders of giants - nothing created today can ever be considered to be truly "original".