For pain to be experienced a number of centres in the brain have to all fire at the same time. There are parts of the brain that enable us to localise where in our body the pain is experienced, and there are parts related to emotions, and parts related to preparing us to run away or fight, and other parts which control basic bodily functions – turning them up or down, depending what is the best response to pain. For example pain often inhibits the digestive system and the reproductive systems – what good is digestion or reproduction if you’re meant to be escaping some threat?
So, pain is more than a physical sensation. It’s linked to our emotions, and is part of a survival mechanism that’s connected to ancient parts of the brain to do with self-preservation. The primary biological driver is survival, and pain is part of that mechanism. It’s there to motivate you to change your behaviour in some way.