Napoleon Bonaparte defined history as "a fable retold." Interestingly, the word for both history and story in his language (French) are the same word: histoire. Another wording of this definition is that history is the record of events that suits the powers in control.
Bonaparte's and the other definition notwithstanding, part of history is usually objective and accurate; that is, the record of significant events from the past. Here is one definition that is certainly workable:
History is a narration of the events which have happened among mankind, including an account of the rise and fall of nations, as well as of other great changes which have affected the political and social condition of the human race.
That history changes according to who is in power, or what ideology is prevalent does have some substantiation as educators can attest. For, those who have been teaching History courses for some decades know how textbooks from even as little as a decade ago demonstrate that there are now some different interpretations of events. Or, for instance, if a war's history is examined in an American textbook, and then in a textbook from another country that was involved in the same war, there are usually some differing interpretations on certain events. (There are teachers in the U.S. who have had foreign exchange students and will attest to this. When they read about their own country's involvement in wars and such in American textbooks, these students often argue that the history is recorded incorrectly.)
Literature, too, is history as it is the recording of man's thoughts and emotions and struggles--the history of cultures.
A simple definition from a dictionary is that history is
a chronological record of significant events (as affecting a nation or institution) often including an explanation of their causes.
Perhaps the difficulty lies in finding the "explanation."