We can be nobody in a few different ways.
First, if we take ourselves to be this human self, we can be a nobody in the sense of nothing special. Usually, this is accompanied with a desire to be special, and an attempt to compensate for the belief that we are nothing special.
Then, if what we are notices itself, we are nobody in that the sense of I-Other falls away. There is nobody here.
And finally, when that matures, we may be nobody also in that our life tends to be lived in a quite ordinary way. We are nobody, because our life is not neccesarily anything special in our own experience, and the view of others.