For a very long time written history was primarily what we would today call "political history" or "diplomatic history" - it was concerned with nation-states, wars and diplomacy. Furthermore, it was written by élites and to a large extent the history of élites. The chroniclers of the Middle Ages, who were concerned mostly with recording events (rather than analysing them, as historians do) concentrated mainly on political events, only discussing "the people" insofar as they affected these. This can in part certainly be attributed to the lack of belief in human progress, a concept which was unknown until the seveteenth century - where was the point in recording the activities of the illiterate peasants? They would be much the same tomorrow as they are today.
When history emerged as a profession in the nineteenth century, most historians still held the nation-state to be the proper object of the historian's study, especially those following in the footsteps of Leopold von Ranke (considered by many the father of modern historical method). "History is past politics and politics is present history", declared a holder of the Regius Chair in Modern History at Oxford University. And this point of view has remained tenacious ever since, especially among people would be considered "conservative" - Sir Geoffrey Elton and Sir Lewis Namier to name but two, both of them very influential and admired historians in their day and since. The idea that history is the study of "people who matter", of great men who exist independently of the social forces surrounding them, took a number of blows in the twentieth century that initially looked part of a reaction which might destroy "political history" altogether.
Social history, the study of the great mass of humanity who for many centuries were not structured in political organisations, and hence not considered part of the sphere of the historian's study, is now a well-established school of historiography. But it once claimed absolute dominance, to be the synthesis which bound together all other branches of history. At first it emerged defining itself negatively, "history without the politics", which happened in England under the influence of one chapter of Macaulay's History of England, which discussed "social" issues without reference to politics. But it soon became tied up, especially on the Continent, with the history of the labour movement, particularly the Marxist labour movement, which was evidently seen by the élite as a "new" aspect of their society which they needed to understand. Since then social history has come to be more the "history of society" as a whole, not just the proletariat - thus all classes and masses are now considered proper as part of the historian's study. The claim to absolute synthesis came from the fact that social history qua the history of all society seemed to be an aspect of all types of history.
E. H. Carr, in his What Is History?, written in 1961 and serving as the standard introduction for many University courses up to this day (it is the standard tactic to pit it against Elton's The Practice of History), considered that "the cult of individualism is one of the most pervasive of modern historical myths". In his view, history is mainly the study of social forces of which individuals are a particular instance. In Carr's view, the "great men" who formed history were great because they personified, on a scale above average, the wills of their contemporaries. Thus most people in the Western world were not a part of Carr's conception of history until "the last two hundred years", because they had evaded political organisation and thus never produced great men who exemplified their wills. Carr's view of history as the study of human progress made this seem logical, but since then many different schools of historical enquiry have established their own thoughts on what is significant in the study of history. What Carr deplored as people "knowing more and more about less and less" in fact increases the rich tapestry of historical knowledge - social history teaches us what people through the ages have thought about love, death, sex, family and faith. This is incomparably important and interesting to those who wish to understand the human condition.
This is not to endorse Carr's statements to the effect that the individual is powerless before the social forces he personifies - after the publication of his views he would later rescind slightly, anyway. Had Lenin not died prematurely in 1924, the history of Russia in the 1930s, then of Operation Barbarossa, and of Europe as a whole would have been very different. Historians agree that even if Hitler had died in 1925 and the Nazis never come to power, World War II would still have happened - but the character of the German war regime would have been very different, and European Jewry might not have met such a terrible fate. History is surely the study of individual people and their environment, not one or the other. As Richard J. Evans says in In Defence of History - "In the end, no-one has managed to better Marx's dictum that people make their own history, but they do not do it under circumstances of their own choosing."