Why do we have pain?

Since there isn't a soul who doesn't experience pain in this mortality, I'm wondering what is the need for it? Is pain soul developing, does it advance us to a better place, or teach us something we can't learn without it? Everybody - babies, teenagers, adults, rich, poor, slave, master, Australian, Swedish, Canadian, Brazilian, everybody experiences, physical, mental, emotional pain. Is that the only way we know when we are happy or even have an appreciation for it? Why do we have to have so much of it? Ahh but life is good. I like my life even with the pain.