You ask: 'What is the purpose of existence?'
We don't know how to live playfully, without a purpose. We need a purpose to pull us onwards, we need a purpose to push us onwards. Without purpose we are lost; we need a purpose to goad us on and on.
Why do you need a purpose to your existence? Are you not satisfied with what existence gives you?
Purpose means desire. You cannot believe that you are purposeless -- then suddenly you start falling flat on the ground. Purposeless? Your ego cannot stand without the props of purpose, so you go on creating purpose for yourself, even where no purpose exists.
This existential question is inside everyone: Is there any point to existence? In the first place, existence is not a question, it is a mystery. It is not a problem to be solved, but a mystery to be lived, to be danced, to be sung. A mystery to be celebrated.