Are you asking why?
I think that the reason why studying the past is important is because the past can help us predict the future: so if something happened like this in the past for some reasons and if the same reasons hold today then we could expect to predict the future events.
For this we need to understand the causes and effects of the past events.
For example, we should understand the reasons for fascism in the past to be able to see if there is a potential for it today.
