What is awareness?

I understand that there is no self; yet there seems to be a never changing deeply seated, unfindable awareness attached to a human body that observes the sensations that arise and pass away. This awareness continues to observe the body, life after life. It sits quietly as the body reacts and reacts until it discovers meditation and begins to stop the cycle. What is the nature of this awareness? I can't make sense of the apparent contradiction that there is no self, yet this 'awareness' has to follow a series of rebirths until this 'individual' is purified, at which time they are fully liberated. I understand that there is no self. There is nothing definable about the self which makes perfect sense to me. But there is most definitely an awareness. What is this awareness? Is every living creature in the universe a unique awareness with identical properties? Are we all the same awareness? If so then why are we dealing with karma as discrete individuals?