So there are all these answers to this floating around as to how unlearned lessons are repeated, it lets us know where we came from, etc, etc.

I think that's crap.

Historical situations do not repeat; the details are always different. Trying to apply history at anything more than a superficial level is huntin' for a hurtin', as my friend says. You'll come to the wrong conclusions because the situations are not actually parallel. Moreover, that's not actually studying history, that's studying the present through a historical lens.

To me, and I speak as a graduate student at a T1 research university, most of the stuff that academic historians do does not possess any actual merit beyond the intellectual exercise, and even that small merit is only intelligible to other academic historians.

The true importance of historical study is its methodology, its mindset. Historical study is an act of sympathy, of apology in the most fundamental and original meaning of both words. Correctly done, it is the full and unbiased understanding of the people of the past as they were and as they saw themselves. We are, to borrow the brilliant phrase of a terrible bigot, speakers for the dead, and our essential purpose is to cultivate a mental approach to those who are not ourselves which seeks to understand, rather than to categorize and judge.

This is not the natural state of the human mind. To quote the late, great David Foster Wallace:

Think about it: there is no experience you have had that you are not the absolute centre of. The world as you experience it is there in front of YOU or behind YOU, to the left or right of YOU, on YOUR TV or YOUR monitor. And so on. Other people's thoughts and feelings have to be communicated to you somehow, but your own are so immediate, urgent, real.

The promotion and indoctrination in a historical mode of thought is thus the indoctrination in a way of approaching the world that attempts to separate us from that basic impulse to understand the world based on our own preconceptions. Teaching this is what historians do. All that stuff with dates is just a side hobby.