Imagine a really big family with lots and lots of people. This family is called the Davidic line. They all come from a man named King David who lived a long, long time ago.
King David was really important because he was chosen by God to be the King of Israel. This means he was in charge of all the people who lived there.
When King David died, his family continued to be important. They were like a special group of people who had an important role in Israel's history. They were like the royal family, but instead of being called by the name of a country, they were called by their ancestor's name: David.
The Davidic line was really important because it was believed that a very special person, called the Messiah, would come from this family. The Messiah was going to be someone who would save the world from all its problems.
Even though King David and his family lived a long time ago, people still talk about the Davidic line today because it is part of Jewish and Christian history. They are like a symbol of hope and promise that one day there will be someone who will bring peace to the world, just like it was promised a long time ago.