There is also a possibility that over evolutionary timescales we'll become less intelligent, and our tool making and use will become rote and externalized into

There is also a possibility that over evolutionary timescales we'll become less intelligent, and our tool making and use will become rote and externalized into networks of people (and devices). There is some indication that this has already started. Once it became impossible for a human to know more than a fraction of the knowledge that is relevant to their decisionmaking, bigger brains were no longer unequivocally better, and socially networked brains started making better decisions (early anatomically modern humans had bigger brains and thicker skulls, on average, than we late moderns). Something related seems to have happened much more recently with the advent of widespread literacy that strongly selected for silent reading comprehension and associated minor neuroanatomical changes) while deemphasizing the ability to recall words (and possibly other things) verbatim. We certainly aren't smarter than the ancient Greeks, but we are better at a bunch of skills and abilities like silent reading, and possibly considerably worse off in other ways.