I share the same thought process regarding fundamental self. Main reason being is that we are in a constant state of change. We are constantly adapting to environment and aging and changing if we choose to accept that fact or not. And what can be "fundamental" if our perceptions and concepts are in a constant state of transformation?
River flows yet the same water molecule never flows twice on the same river, because by the time it would get on the river, its shape has already altered. The same human cells replace themselves, except for some nerve cells. Seems like the only "fundamental" really is the constant change of everything.
Exactly!