We all ask this question at some stage in our lifetime. And it is always there in the subconscious throughout our lifetime. And the best is that all the answers that come from within are the right answers.
However, here is an approach:

We are not human beings on a spiritual journey… we are spiritual beings on a human journey.

We are all small micro pieces of consciousness that are part of the super-consciousness (god u may call it)…

It is the journey of the soul, the soul incarnates & reincarnates on the ‘earth school’ & with each lifetime there are lessons we learn & unlearn…. the laws of cause & effect are applied through our karmic patterns (karma – thought, words & deeds).

Our core purpose is to connect with our spiritual selves. To remember that if I am part of the super consciousness all others & everything in the universe too are part of the same superconsciousness… I am you. You are me…

the best answer for ‘who am I’ can be found in ‘the Geeta’ where Lord Krishna explains to Arjuna.

Deeper states of meditation do help you find ur own answers to the question too!