There was no beginning in time - because all Beings are eternal, including you and me. There is no time at which we were not.
What are Beings? Beings are uncaused causes, origins of action - not merely consequences.
And all Beings are self-sustaining and indestructible; beings develop, they transform - but they never began, they always were; and they never end.
So, there is no primordial self, no irreducible minimum to which has been added. Rather, when we became children of God, our Heavenly Parents; that was A beginning - the beginning of us as Persons.
However, it was not The beginning - we existed, and always had existed, before we became children of God. And that is (in a sense) why we can be free, why we are agents. We develop and change through time, but we have no beginning, we are defined by lineage - we always were.
That is who we are.