What is I?

Is it what you think you are?
Or is it what you really are?
Are you, I?
Or am I, I?
Why can't your I be my I?
Who created this I?
Is I the same, all through your life?
Is the child I different from the adult I?
If I is not a constant throughout your life, can I be defined?
If I cannot be defined, does it mean that you are many people in your life?
If you are many people in your life, who is the real I?
Is there such a thing called the real I?
Or is I the figment of our fertile imagination?
Is it the label we give to our ego?
If so, what is this ego?
Is it the sum total of all our feelings, fears and frustrations?
If that is true, then who gave us these feelings, fears and frustrations?
Did it come from within?
Or did it come from outside?
If it came from outside, then how is your ego, yours?
If it came from within, what is that within?
Is it the heart?
Is it the mind?
Is it the soul?
Is I a different entity from all these three?
Does a man with an artificial heart have an I?
Does a man with no memory have an I?
Does the soul have an I?
If so, then what is this soul?