The 'Algernon Argument' says simple smart drugs won't work, because we already evolved brains optimized for using the substances available to us efficiently. In the same vein, it'd be bizarre if we developed bodies that work ok for a hunter-gatherer lifestyle, but respond fantastically well to using a Bowflex for 15 minutes a day.
So if modernity is going to give us exercise benefits, it's probably going to be from changing our options or preferences around the stuff that's always worked. (And we know this is true for other animals; domesticated horses can do any one task better than a wild horse, but they lose on adaptability and resilience.) Good childhood nutrition and disease avoidance make us fitter, readily available protein probably helps too. Knee braces might help avoid cumulative damage over our longer lifespans. Since most of us don't want to exercise 5+ hours each day, things like cycling and swimming might be more efficient exercise than walking. And of course professional athletes simply pursue different goals, with consequently different tactics.
But if something comes around claiming to be better for our general health than spending a lot of time doing varied, progressive exercises, it's time to be suspicious.