In high school, Rupp ran a 16:40 5K off of no running focused training. (Source - 14 Minutes)
Bill Rodgers ran 20 miles at 6:30-6:00 pace off of around 40 miles a week of unfocused training (just tagging along with Amby Burfoot). (Source - Marathon Man)
It's no wonder I'll never get anywhere in the sport against these natural talents.
Anyone else you want to add to the list?