> breadth and depth of understanding about psychology have improved dramatically
Provide one tiny bit of evidence for this. Do you seriously think that Shakespeare (for e.g.) did not have a profound understanding of human psychology?
If he did it's not shown in his writing, or really any pre-20th century writers really.
there's a reason Harold Bloom titled his book about Shakespeare The Invention of the Human
not who you are replying to - but: Shakespeare was limited by the number of interactions he had with humans. He did not have the internet.
We also have neurology as a science now. So that's one bit of evidence for the claim.
Of course Shakespeare had a profound understanding of human nature. And of course he did not have the working vocabulary and knowledge base of modern psychology which has been built up over time by many humans working together. Two things can be true.