IIRC, the Jamaicans basically defunded their drug enforcement, hired known pro-doping coaches, basically have a "team chemist". The Jamaican sprinting explosion followed.

I want to make clear that Jamaica is not an outlier or "bad guy". Really they are small fry in the industrial olympic sports machine. What they really are is a window into what the big time countries do.

It of course helps that sprinting is a national obsession in Jamaica, so the best athletes do sprinting. But that's been true for a long time.

Personally, I do not think humans can run faster than 9.90 in the 100m without "aid". or under 20.00 in the 200, or under 44 in the 400m.

I do not think a human can run faster than 13:00 in the 5000m, or 27:00 in the 10,000m, or somewhere around 2:08 in the marathon.

But those are personal opinions.

Don't worry, it will be all 50 eventually. The 100m is often decided by photo finishes and yet, Usain Bolt has had to look behind him AND slow down before crossing the finish so that he's not too far ahead of the others.[0]

[0]https://www.youtube.com/watch?v=o-urnlaJpOA

What is more important is that he improved his results during a small atypical time period.