The historical books are just that: a highly selective account of the history of God's activities in the past, in particular in relation to His people Israel and their leaders. This includes both highlights and low-lights - often more of the latter than the former. You can find more information on some of this (including a page on God's purpose with the Jews) in the Nuts and Bolts section 'History Matters'.
At first glance it might seem that these books are merely a nationalistic account of Israel's past, But closer inspection reveals that this is not the case. One of the remarkable things about the Biblical writings is that despite being predominantly Jewish in origin, they are not supportive of many of the things the nation of Israel did in its history. These accounts are not primarily accounts of Israel's past as an end in itself. They are accounts of the interraction between God and His people.
And that, in a nutshell, goes a long way to explaining why they are highly relevant. God used His relationship with Israel as a teaching mechanism for the way in which He deals with mankind and the world at large. The relevance of so much of that Old Testament history is because of what it teaches about God, and about what He wants from us (and the implications if we do or don't attempt to confirm to His wishes).
Although these accounts appear to be comprehensive and contain a great many facts, there is far more that they don't tell us. The point is that we have been told enough to piece together what we need to know, not just about the historical facts about God's people, but, more importantly, what there is to learn from it.
Lives of faith
Often the narrative pace will slow down to focus particularly upon certain characters and their relationships with God. We meet real men and women of faith, who struggled to put into action what they believed about God, sometimes in some very trying circumstances. As the New Testament makes plain, there is much that can be learned from all this.
These characters are not some sanitised or idealised superheroes of faith, spiritually airbrushed with a pious gloss. No. These characters are presented warts-and-all. There are characters who are deeply flawed - Samson springs to mind as an obvious example - but the great thing is that God can work His purpose through human beings despite their faults and shortcomings. That's something which is very encouraging.
While we've classified 13 Bible books in this 'History' section, that's not to say that the other parts of the Bible are fiction. Far from it. The Law of Moses (Genesis through Deuteronomy) recounts history which is absolutely critical, and the gospels and Acts depict the historical work of Christ and the formation of the early church. In a sense, those parts of the Bible are subsets of this 'History' section. We've given those books a section of their own, however, since they are so distinctive and group together so naturally. That leaves us with the thirteen books which begin with Joshua and the conquest of the land of Palestine by the Jews, and contiues in fairly continuous though selective fashion until the captivity in Babylon and the return of some of the Jews to their land which began under the decree of King Cyrus of Persia. A brief survey of the chronology of all this can be found here.
Q: Questions coming soon!
A: And answers too...!