It's not a very intuitively appealing 'invention', but string and rope - binding fibers together to make them stronger - has been going pretty solidly for nearly thirty thousand years, starting with vines or reeds, then moving on to animal hair, wool, hemp and finally the synthetic fibers we use today.

It's kind of an annoying answer, because string seems to toe the line between technology and intuition, but it is at least one example of toolmaking unchanged for millennia.