Original ideas are nice, but are by no means necessary to start a successful business. Air bnb and Facebook are a couple successes that spring to mind that are really just an improvement on other original ideas. Truly most businesses (even in tech) are just a better mousetrap. Ignore patents and don't overly focus on coming up with the next big thing and concentrate on how you might execute something better. Better design, engineering, marketing... What do you bring I the table?

In fact, this may even help you approach a more original idea from a tangent or pivot from your original business.

Just look at PG's comments and essays. He looks for founders with potential more than he looks for mind blowing ideas.