One of the things I love about this work is that Nietzsche expends little effort establishing exactly who precipitated which shifts, but instead attaches grand shifts (and poles of meaning) to figures who are iconic of them. (Though as you put it, Socrates is a solid candidate, and it's hard to think of anyone more significant to this shift). It's almost as if this work about the importance of mythos is itself written in a somewhat mythical style.

Regarding the idea that the thirst for knowledge is universal, I'm not positive I agree (or rather, that this type of thirst for knowledge, systematic, all-categorizing knowledge, is and always has been inherent to man, rather than conditionally, contextually developed), but it certainly has some strong proponents. You brought this quote from Aristotle to mind, which I received via Daniel N. Robinson's lecture on metaphysics:

"ALL men by nature desire to know. An indication of this is the delight we take in our senses; for even apart from their usefulness they are loved for themselves; and above all others the sense of sight. For not only with a view to action, but even when we are not going to do anything, we prefer seeing (one might say) to everything else. The reason is that this, most of all the senses, makes us know and brings to light many differences between things."