@William said:
It would be very easy to make the case that Bach is the greatest musician and composer who ever lived.
Yes - very very easy.
But of course you then get into genres and styles. Basically, more intelligent and studied music theorists and historians than I would say that all music is a sort of continuation of what goes before. Ergo, Mozart takes elements of Bach - Beethoven takes elements of Mozart, Haydn and Bach and so on and so forth.
It's also worth remembering that Bach did not invent the Baroque style - he and Handel were just complete masters of it in many different ways. One, seemingly not driven solely through the constraints of payment with an enormous bias toward so-called sacred composition - the other far more commercial in his outlook and certainly more than capable of writing sacred music for as much money as he could get. Either way - they were both 'true' geniuses.
So we now go from 300 years ago to today. Jaded people could be forgiven in not necessarily seeing that much in the way of any improvement.