When I think of the question “What is I?” I think it is one that does not have one answer. “What is I?” is a question that can be answered directly.
I could be interpreted as everything that defines one as I. Once a part of I is lost, it is no longer I. I is so significant that it must always remain I to have that definition.
I is very complex. I includes everything of ones being. I is everything that is meaningful to what we are. Without I we are nothing.