I don't believe there is anyone I've ever met whose thoughts were original to them in all particulars. I think it has been very seldom where I have met anyone that has had one original thought in their head, I'm pretty sure most thoughts, including mine were thought somewhere else and transmitted via some media. Probably in most cases the only originality lies in the assemblage of the thoughts and how they interact.
I thought I was quite clear that I did not believe everything has been thought before, but only that most things have been thought before - or more specifically that most people think things that have been thought before but in new configurations.