Fitness, or maybe athleticism is a better term, is not what many on this site think. You can argue all day what constitute athleticism but it's some combination of speed, agility, strength, power, technique, endurance, etc. Obviously there's overlap and interplay between some of those concepts.
Great distance runners have incredible endurance, they have great technique for distance running, and that's about it. Whether you like it or not, distance running is overall a pretty unathletic endeavor.
Power lifters have immense strength and technique, and absolutely nothing else. You can argue that's pretty unathletic too.
(Olympic) Weightlifters have immense strength, power, technique, and if you've seen those guys train, you know they're freaks. They're insanely athletic but couldn't do a 6 min mile without a lot of practice.
Anyway, if a random 35 year old at my office with no track background proved to me he could run a 65s 400m, I'd be way more impressed than him running a 17:00 5k.