The main purpose of history, other than the simple fact that we human beings seem to want to know things for the sake of knowing them, is to help us understand humanity and what we are like as human beings.
It is often said that those who do not understand history are doomed to repeat it. This saying hints at the purpose of history. History can, it is hoped, help us to avoid making the same mistakes that have been made in the past. If it is to do this, the study of history must teach us things about how we as humans react to certain conditions and events.
By looking at history, we can understand something of the diversity and commonality of the human experience. We can see how various peoples have reacted to things like industrialization and globalization. We can see what sorts of choices people have made that have led to disasters in the past. These kinds of knowledge allow us to have a greater understanding of how human beings work.
As a practical matter, this is the goal and aim of history. It aims to give us the ability to understand humanity and, by doing so, to better understand the choices we face today.