After David’s death, his son Solomon becomes king, and although Solomon is exceedingly wealthy and wise - in the end, he trusts in his own wisdom rather God’s, and he chooses political comfort rather listening to God voice. From then on the kingdom of Israel declines. It weakens and divides into two parts - a northern and a southern kingdom. Over the next 400 years each Kingdom has it’s own kings - most of these Kings lead the people to completely ignore God and his commands. Occasionally there are Kings in the Southern kingdom who are like David - they do trust God, they recognise that they’ve sinned, and they try to lead the people back to trusting God, but there’s never lasting success. Things get so bad that God ejects them from the land, and his people are taken as prisoners to live in foreign places.
If God’s people are ever going to permanently experience life and peace, they are going to need a leader who is better than David. They need a King who is able to do something far greater than win them temporary peace from a few human bullies. The need a King to come and rescue them from their closest and most unconquerable enemy - sin itself. It’s sin that keeps getting in the way of them receiving the blessings promised to Abraham. Without a permanent fix to sin, there’s no permanent peace.
The Scriptures quoted are from the NET Bible® http://netbible.com copyright ©1996, 2019 used with permission from Biblical Studies Press, L.L.C. All rights reserved