There are different theories for what is in fact the main purpose.
For some the purpose is to serve others around them and to the the world a better place.
For others the purpose is to live for themselves and take what they can.
For people in religion it is bringing glory to their god by following there commands. While also bringing others to the religion.
For some it’s that we are part of the circle of life. We live then we later die.
But my most favorite is that we all impact each other. From the day we live to the day we die, we make an impact on the world. It is false to say that a person can in no way make an impact. So purpose in life is really about what impact we want to make on the world and what steps do you need to take to make the impact. What kind of an impact do we ourselves want to make to create a better future. Every life matters and our purpose in life is something very complex and unique to each of us.
Hope this helps