Once upon a time, “well-read” meant Plato and Cicero.
Now, most of what people refer to as “great” literature seems to come out of the 19th and 20th centuries, which is when the world began to lose it’s damn mind philosophically.
For me, well-read means John Locke, Thomas Hobbes, Adam Smith, Montesquieu, Frederich Hayek, Milton Friedman, Thomas Sowell, and Walter Williams.
(I also love C.S. Lewis).
You should add Evelyn Waugh, Walter M. Miller, G.K. Chesterton, and Tolkein to your list.
The rise of English Lit. as a field of study coincides with patriotic gestures during the two World Wars when Classical Studies - being so associated with stuffy German Philology Professors - became unfashionable.
For me well read really means nothing, most of the folks who talk about it are ego stroking. At least some of the ones you list off I can respect.
That's true, and they meant that they were read in the original Greek and Latin, respectively.
Also, your point about Rowling actually being today's Cervantes is a decent one. Rowling isn't anywhere close to being the greatest living writer, a honor that I believe would likely go to either McCarthy or Roth, I can't name a single good, let alone "great" novelist under the age of 60 - although I'm sure many would argue Jonathon Franzen is great.