Ah, you’ve taken a shaving off of the worldview dichotomy there...
Leftists believe that they are smarter than any generation that ever lived because, well, they are born when there is more information available to the individual, ie, themselves.
They believe that man is evolved and evolving, and therefore more advanced than his ancestors; more moral and intellectually powerful. They believe man is perfectible, and that some are more perfect than others and should be put into power to impose their superior vision on the rest of us.
Spot on. It's not that we know more than our ancestors. We just know different things.