History is about the past. One must be mindful that rehashing the past means the information is static, and can be (and usually is) filtered. Humans detail the past through stories, typically in the form of image, video and words. Even if the story told is with perfect honesty, it represents a source of communication (information transmission) error on several notable fronts: (i) perceived and expressed through the point of view of the author/s; (ii) closed loop of space and time within which the story takes place; and (iii) difficulty in defining and communicating qualia. There was a stream of information, some of it more consequential than others, that led into the circumstances painted in the story, and there was a stream of information that came out of the story. It is (seemingly) impossible for a human to perceive, let alone detail, this information flow into a finite storyline. The best we can settle for are approximations of what "happened", of what led to that happening, and what came after. The better the explanation, and harder it is to vary, the more reliable the story of history.
Studying and making use of history is complex. For one, due to the necessity for a background of the consciousness (awareness of the universe) of that period itself. For instance: the world pre-1900 was one filtered through the understanding and application of Newtonian Physics. The things that were built, the decisions that we made, were done so through this understanding. They simply could not have built computer chips, for instance, because they did not have the combination of knowledge in quantum phenomena and materials science that was present in the 1940s. Another example: the world pre-Newton and the "Age of Enlightenment" in the 17th century, was one often filtered through the lens of religion, of myth. One insight we can glean from this is that the human world would have been more fallible since the explanations upon which humans relied were themselves based upon variable factors from empirical experience instead of explanations with fundamental reach into the future. Thus, two important questions to be aware of when looking at the present, in context of the past, would be: (i) what is the relevant consciousness now and then; and (ii) what else happened, before, during and after.