Why were the things that happened to Israel written down in Scripture?
The things that happened to Israel were written down as examples and object lessons for later generations, so believers might learn from them. Scripture teaches they were recorded for our learning, warning us not to lust after evil things or become idolaters as some Israelites did.
Les explains that I Corinthians 10 repeats the principle from Romans 15:6: all these things were written aforetime for our learning. The events that happened to Israel were examples and good object lessons that told a distinct truth. God was not well pleased with many of them, and they were overthrown in the wilderness. Les compares these accounts to flannel graph and object lessons he loved as a kid because they could impact a child's mind. The intent is that we should learn not to lust after evil things as they did, nor be idolaters, as when the people sat down to eat and drink and rose up to play, which points back to Exodus 32. These things are just as applicable for us.
Now these things were our examples, to the intent we should not lust after evil things, as they also lusted.