Those athletes were maybe just more inclined toward running or certain things in their lives made them fast. Sage Canaday - 2:16 marathoner, said in peak 1500m shape, he couldn't break 56 for 400 meters and only ran 2:00 for 800m(so 2 laps at mo's 5k pace.) Idk, maybe in a time where we hunted for our food, fought, only the fit survived etc... Or maybe somebody inclined towards middle distance/sprinting but not just any runner. 60 is still fast, I think you don't realize how fast a runner you actually are. A 51 second 400m highschool runner is gifted.