Here's is a thought experiment to demonstrate why in my opinion , self-awareness and consciousness is such a mysterious phenomenon:
Imagine i attach my laptop with a accelerometer type sensor that can measure impact force e.g. the kind used in car test crash dummies. Then i write a little program that basically generates screaming voices depending on the threshold of the impact on the sensor . Higher the impact more painful sounding is the scream . afterwards I proceed to punch the sensor again and again and hence my computer starts screaming .But in this scenario i think everyone would agree that the computer isn't really genuinely "feeling" pain and aware of it in the same sense as say a human would have been .... it merely behaves as if it is self-aware yet it is not really self aware. for example it doesn't ask "why i am being hurt ? ". It would be absurd to attribute any self aware to it.
But now fast forward to 1000 years in the future where we have managed to create robots with exactly the same level of emotional and intellectual complexity as the human brain posses . Now if i proceeded to brutally beat that robot and as a result the robot starts crying and screaming , again , just like the case of my computer , we should still technically say that the robot isn't really self-aware of the pain . its just random codes behaving as if it is self-aware. i.e it doesnt posses an inner subjective sense of self which can experience the pain.
Here is where the puzzle arise . As per physicalism which seems to be supported by science atleast in the context of mind-bran relationship, aren't humans also like extremely complex robots ? if so then why is it that such a robot need not be self-aware yet we are? what is the thing that causes that difference ? THAT is the fundamental puzzle of consciousness .
In this post i am merely attempting to lay out the problem . The relevant solutions are to be left for a later time i am afraid.