There's a difference between being born into a world where you are taught you have a purpose defined by God, the universe, etc., and being born into a culture where you are taught you need to find your own purpose.
It's both. You have a purpose defined by God, but you have to understand what it is and the journey is your own. There are a lot of hints, explanations, personal stories, but you have to do some work to understand what they mean.
The historical evidence is pretty clear that the modern idea you have a unique purpose you need to find for yourself started to become common in the 18th and 19th centuries. Before that, purpose was largely a dictate cast upon all members of the society.
Whether people think it's God dictated or it's self invented, sounds to me like people acquire purpose.