Someone once told me there really isn't any new idea out there. We're all repetitive in a way, but like you rightly stated, our thought patterns differ and will always add their own unique variance to to our opinions...especially when backed by experience
I think the idea of "no original idea" is flawed, because there are incremental changes from old ideas. Also, just because someone else thought of it, if that wasn't known to the new thinker, isn't it original?