HUMAN BIRTH IS PRECIOUS, they say.
Life is remarkable and superior (if at all) to other creatures only because humans get to experience life and can express it.
And that to me sums up all *purposes* associated with a life.
However, both these aspects of life - experience and expression - are powerful volatile forces.
Journey towards Nirvana then is to minimise on this volatility by expanding experiences and restricting expressions. And also restricting experience and expanding expressions.
Certain environments call for a balance between experience and expressions with no particular emphasis on either expansion or restriction. Whereas some conditions call for a suppression of both these aspects of life.
All major spiritual traditions, ancient or modern, subscribe to one or more of these tenets.
Related post (Einstein and miracle quote): A Dialogue on "Ciencia Contra Religion La Verdadera Diferencia" (Science vs religion: the real difference).