"Remember that you are mortal, and you have a limited time to live, and in devoting yourself to discussion of the nature of time and eternity you have seen things that have been, are now, and are to come."
Given Nietzsche's antipathy to Stoicism and his somewhat embrace of at least some aspects of Epicurus, I expect this article to have relevant material on what separates Epicurus from humanism.
I believe Epicurus would agree with this characterization of Plato, which the writer posits to be Nietzsche's analysis. And so I think this viewpoint is helpful to us in assessing Plato from Epicurus' viewpoint:
I don't think there's anything unique or novel in this summary of Plato's position, but it strikes me as accurate and a very good summary to keep in mind as we think about Epicurus' viewpoint, and how it is a direct response to and attack on this perspective: