So why would we celebrate the birth of a baby born about 2000 years ago? Why is Jesus so special?
First a little analogy: Imagine a man who had a terrible disease which would cause his death, and there was a cure, but this man was poor and could not afford the medicine. He tried as hard as he could, but still could not find a way to get the money to buy the medicine. Then someone unknown to him, comes along and gives him the medicine as a free gift. Whats more is that generous person sold his house to buy the medicine for that man. He excitedly and graciously accepts the gift and is cured.

Well here's the news for you and me. Each of us has a terrible disease which causes our death (physical and spiritual), we  all die. Our sin has given us this disease. In fact the bible tells us we earn death, like a worker who earns wages gets money, our sinful actions earn death (Rom 6:23).
We cannot do good works to pay for the cure, we are too poor. But rather God paid a great price for the cure, and offers it to us as a free gift.
The bible calls Jesus "Immanuel", which means "God with us" (Matt 1:23). Jesus came to earth to satisfy Gods righteous judgement, and pay the penalty for our sins. So Jesus was born to die for our sins, so we could have eternal life through him.
God calls us to repent (turn away from our sinful life to God), and put our faith in Jesus who died on the cross for our sins, so that we might have eternal life with him. Jesus is our cure.

Thats why he's special, and why we celebrate Jesus!