This movie tells us that even though the world is a horrible place sometimes, there's always a place for love and that everyone is worthy of love.
Leeloo is a perfect being. And she finds it tragic that people kill each other. She doesn't understand it.
But even with that, she finds strength in not giving up on them and loving them and loving someone as flawed as Korben.
And Korben, while flawed, is a good person, who is very selfless and very brave. He has also been hurt by this world but he decides to do the right thing and he finds that teaching someone that love exists is so rewarding.