You need to be able to run about 13.5 in a 100m sprint to run sub 60, believe it or not, this kind of speed this is out the question for a lot of men. I have seen some sporty fit guys struggle to get under 14/15 seconds despite having an active life and being healthy. However, for the men with enough natural speed to break 60 then yes, this time should not be too hard providing you build up the appropriate level lf endurance to do it. Sub 60 is achievable for 20% of men, that is 1 in 5 and still quite a lot. But sorry, most aren’t getting close. 60 seconds is damn fast for someone who isn’t a gifted sprinter, which most aren’t.
5 flat is rare and you will probably need to run both 60/400 and 20/5k in order to make this happen. Mile time is most dependant on vo2 max than the other two benchmarks (you can calculate vo2 max by calculating your maximum power output effort for 6-10 minutes). Running all out for 5 minutes is going to be close/slightly above vo2 max. In order to run a 5 minute mile your vo2 max needs to be around the 56-58 ml/kg range otherwise you just will not have the level of aerobic power needed to run that fast for that long. Science-backed studies show that the average male is around 38-44 ml/kg and that the average benchmark for improvement in vo2 max plateaus at around 15-20% WITH optimal training. A 20% improvement in the median guy (41 ml/kg) would be 49.2 ml/kg fully trained, that is good for a mile around the region of 5:40 and 6:20 so as you can see, absolutely nowhere near sub 5. The study said the outliers improved by 25% so you take the high end of average untrained guys (the ones with more talent) and their untrained max is 44 ml/kg, with a 25% improvement this guy is now able to take in 54 ml of oxygen per kg... STILL not fast enough for sub 5 and would probably be good for around a 5:15, now maybe if this guy had exceptional speed for his level then maybe, just maybe he could sneak under 5 but that would require him to be more sprint based anyway. Based on all of this, I say only about 3-5% of the general male population are breaking 5 if their lives depended on it, even near-the-cream-of-the-crop naturally athletic guys cherry picked from the general population would struggle with this.
And as for sub 20, I would say this is achievable for 50% of males. By far the easiest of the three, by far. Looking at the vo2 max figures, Mr. median would top out at around a 6 minute mile FULLY trained (give or take 30 seconds). This is *just about* fast enough to sneak under 20 minutes for the 5k with some endurance training. Most of the fit males I know on sports teams, in the army, etc can probably run between 21 or 24 minutes for a 5k - or at least that’s where I’d put them. I don’t believe anybody is going to be optimally trained aerobic-wise unless they actually train for a distance, give these guys about a year of hard aerobic training with a little mileage and they would break 20. The 50% of the male population who couldn’t physically break 20 due to vo2 max being too low to do so (and yes, vo2 is is pretty musch the decided in success from 1500 to 5k) then I am guessing the below average males would top out somwhere in the 21-25 minute range.