You have put your finger on the key criticism of much of Jane Austen´s work - its clear and restricted focus on a very small slice of English society in her time. Critics have argued that the way major events such as wars and colonialism and slavery are only in the most oblique ways refered to indicates her limited scope and vision. And yet, for me, I wonder if this "limitation" is actually symptomatic of the preoccupations and point of view of females in this time. To put it bluntly, females were not concerned with such events, or only in as much as it meant the coming and going of various regiments with their ranks full of potential husband fodder. We are privileged to see a very different point of view of life at these times, and obviously we need to be aware of its limitations, but at the same time we need to focus on its advantages.
Interesting question. Much of what is written in history books concerns wars, battles, monarchs and the big advances in knowledge. What Jane Austen does is different. Through her, we get a picture of what life was actually like for people living in the early 19th century. By the way she writes of what is acceptable behavior, and the way people think of each other, we get clear ideas of the forces shaping the culture of England at that time. Women could not inherit property. The first born son was the heir to the family fortune, and later-born sons had to find work in areas acceptable to their social class, for example the ministry or the military. Austen never sits down and spells those things out, but shows them by the way her characters interact.
Austen shows the history that is not in the history books, except peripherally, and brings it to life.