The "cohesive narrative" stands alone. History exists only on its own terms. You cannot look at something that happened in history and say: we can do this because it happened then. It is not absurd, it is the basic aspect of how histography is taught in university (and btw, if you study politics...you will find the same idea, "path dependence"...you see parallels in every social science because it is a fairly common mistake made by people who haven't thought about the issue deeply...the "why don't you be like Denmark" meme is a classic of comparative politics).

I am not saying that the present is the only lens (again, you haven't even started to understand what I wrote). The point is that the present is the only present. The past can only be understood in it's own terms. You are not constrained in any way because the past provides only information about the past, not the present.