The perception of ‘I’, which is your core identity, is humming almost always in the background of consciousness during your waking moments.
It is lost when you sleep, but activated often when you dream.
It can also be lost when you ‘lose yourself’ in engaging activities or absorbing sceneries or in certain meditative states.
This perception of ‘I’ is the same one as when you were a child. For you feel and know that you are essentially the same person, despite the years, despite the physical changes, despite the differences in your likes and dislikes.
You can change your name, you can go for plastic surgery, yet:
you still feel and know that you are you.
This is the perception of ‘I’.