But what made the likes of Newton/Einstein/Beethoven etc. stand out is how much they achieved given the limitations of the times they lived in. The reason I picked those three is all of them were known for being able to devote huge amounts of dedicated time to their specialty (Newton especially, who from memory developed most of the ideas in Principia while under effective lockdown during a smallpox outbreak. But unlike those of us under lockdown in recent years, there were no electronic gadgets distracting him either.)
Fairly sure Fleming didn't have anything like the distractions around now when he developed penicillin nearly 100 years ago!
The other examples seem to be very much group efforts, and I'd be impressed if the average guy or girl on the street could name the key figures involved.
It's possible we've simply reached a point where all the breakthroughs that realistically could be achieved by individuals have already been made, or that in the world of art there's simply too many artists able to readily share their creations with the world for individuals to stand out to the degree great artists of the past did. But I honestly don't know - it just seems that with so many more of us with access to resources and levels of education prior generations could only dream of we should be able to achieve a lot more than we have been.
It's much easier to be a polymath when the subjects are an expert in are pretty relatively unexplored. Today people spend their whole lifetime studying a deep branch in a single field, because the tree of math/physics/bio etc.. is much much more explored.
