For example, we learn that Jacob was 77 years old when he and Rebekah deceived Isaac into repentance, and when Jacob fled to Paddan-Aram to find a wife. His twenty years of service to Laban were from the age of 77 to 97. And Joseph was almost certainly sold into slavery before his brother Benjamin was born, so that the first time he heard of Benjamin was when he overheard his brothers in Egypt.
We learn of contemporaries: Abraham was still alive when Jacob and Esau were born. Isaac died just before Joseph was released from prison, reminding us of the death of the high priest that sets people free (Numbers 35:28, 20:28; Joshua 24:33; 1 Samuel 4:18; Jesus). Samson, Samuel, Jephthah, and Jephthah’s daughter (who almost certainly served at God’s tabernacle rather than being put to death) most likely ministered at the same time, so that Samson’s death in Judges 16 was almost at the same time as the defeat of the Philistines at Mizpah in 1 Samuel 7.
Saul was close to or beyond 40 years of age when he became king, since his son Jonathan was a capable fighter at this time. This adds greater depth to the virtual adoption of Saul by Samuel in 1 Samuel 10:11-12; even as a 40-year-old, Saul was to heed the voice of Samuel his father. This also underscores Samuel’s grief over Saul’s fall (1 Samuel 15:35). If Jonathan was at least 20 years old at the start of Saul’s reign, and Saul reigned for 40 years (Acts 13:21), and David was 30 at the end of Saul’s reign (2 Samuel 5:4), then we see that Jonathan must have been David’s senior by at least 30 years. Jonathan was a truly humble and godly man.
But we gain sad insights as well. For example, we would like to think that the Song of Solomon, possibly written to the daughter of Pharaoh (1 Kings 3:1), was written to his first wife. For theological reasons, the book of Kings stresses that Solomon began running his race well. But we learn later that Solomon was married to Naamah before the daughter of Pharaoh (1 Kings 14:21 taken together with 1 Kings 11:42). So we see that even at his accession, the seeds of Solomon’s sin and fall (Deut. 17:17, etc.) were being planted.