Descarte' famous saying, "I think, therefore I am." is worthy of analysis.
I can only say "I" if I don't look.
If I do look, the best i can come up with is a concept which I call I.
If mind investigates then it can only observe thoughts arising.
Also it is implied that thinking is a deliberate action, but investigation of this shows that thoughts happen to me, not by me.
Am is definitely correct.
Something is aware that this is going on. Perhaps it is Consciousness ?
If the am is happening to that something, then the something is before mind, so it is reasonable that the mind can't know what produces it.
When we look in a mirror we don't see ourselves. We see an image of how we look. It in no way represents more than a visual representation of our body.
Perhaps the mind is like a mirror reflecting a partial representation of the "what" ?
If Descarte were more accurate, maybe he would have said "Thinking occurs, therefore Ego can believe it is I."