As with most things, C.S. Lewis had a unique view of history. For him, the really important bits were the stories—he makes a distinction between actual historical realities and the idealized versions of them handed down which make heroes and villains of mere men and women. It's not that the stories are completely false, but their value is for character-building, not as factual data.
The tales of George Washington's bravery in battle, coolness under pressure, rigorous truthfulness, and unflagging piety may accurately preserve the essence of his temperament and nobility, but not all of them are strictly historical. The point of these stories isn't to impart facts, however, it's to offer an example of goodness for the rest of us to emulate.
Getting the facts right is still important, though. As Christians, we can't afford to have a false understanding of "the old days." Mankind is fallen, and the story of his sojourn on Earth is filled with war, suffering, disease, unfaithfulness, pride and envy; a study of history that omits those elements is both false and useless. False, because it is incomplete, and useless, because it tells us nothing of the human condition or our current situation.
It's a bit of a mystery to us why non-Christians are motivated to study the past. For believers, the end goal isn't just acquisition of facts about events and cultures, it's the instillation of a thoroughly Christian worldview, an understanding of the course of the human endeavour as decreed and guided by God Himself.
The story of Jesus Christ is central. It is the only history story that fulfills the character-building element Lewis looked for, while remaining absolutely true in every detail. Man is fallen and he does struggle against God, but through Christ there is hope of redemption, a chance to connect heaven and earth through the Atonement. Christ is the ultimate example of God's providence.
In the Reformed tradition, God's sovereignty is a very big deal. According to the doctrine of divine decree, God has ordered all things that were, are and will come to be for His own good pleasure and glory. His hand is thus present everywhere, in the privatest private life and the most public and widespread crisis. God is in control, providentially guiding nations, men, and the entire cosmos.
This very doctrine is perhaps what best explains the humanist's interest in history (whether he be atheist, agnostic, pagan). Man's natural bent is to make himself the hero of the story, to show how people can sway the trajectory of all things. God's version is quite different, and the two are naturally in conflict. Resolution may only be found in Christ.
For, while God decrees and guides all things, He has also (paradoxically) decreed man's free will and personal responsibility. Men do change the course of kingdoms, but it is only through God's agency. A proper Christian study of history takes both truths into account, and tells the stories of good guys and bad guys through the light of everything God's Word says about human nature and divine control.
We encourage you to take great comfort and joy in your study of history. Read books, watch movies (carefully noting that a lot of the story is likely to be inaccurate in detail), go on fieldtrips to forts and battlefields and birthplaces. Most of all, talk about these things. The end goal, after all, isn't to know a bunch of trivia, but to understand what God has done and continues to do.
No one knows for sure what the end of history will look like, except that every knee in heaven and on earth will bow to the returned glorious Christ, who comes to judge the living and the dead. What we believe about Him will determine whether that culmination will be filled with joy or loathing (everyone will be terrified). He is the author of history, and its centerpiece; honor Him in your study of it.