Well, I can see how someone would naively think that was true, because only a fixed set of events have already happened in the past, so there is a correct answer.

I think it also stems from the way it is taught in schools, where there is a lot of focus on memorising dates and events etc, rather than on the process of actually deriving them from sources of questionable trust.

Also, the majority of focus in schools (in the UK) is on much more modern history and doesn’t really focus too much on the really ancient stuff and the extra difficulties that arise from learning about it.