There is no such thing as original thought.
Just thoughts that we heard from somewhere else long enough ago to forgot that it wasn’t our own witticism. Other ideas are typically are just built on principles established by those who came before us or are simply copied from those that we meet along the way.
The reason for this is that our world is a very structured and patterned world in its essence, and as beings that are a direct product of our physical environment (no matter if you choose religion or science), thought (and it’s offspring – action) simply follows those same familiar structures and patterns.
Even our creative process is bound by this truism. We simply can’t imagine past that which we have experienced first hand – or through extrapolation of known entities.
Of course, I’m not saying anything new.