What is the purpose of a brain?
To learn and to create new knowledge based on learned knowledge.
You are your brain.
That is your purpose.
I noticed that the more you learn, you open new paths which you didnt know before.
In fact, many things are related, and learning about one thing can make you realize new knowledge about other things, since knowledge about one thing can be applied to other thing as well.
Brain constantly learns, but brain must first learn about things which interest it, and then move on to other things.
Since the brain is made to learn, it means you are made to learn.
And in this century, learning is easy.
You have google and AI willing to explain anything to you.
Its on you to write down and learn.
Writing down is important, because human brain forgets some things or fails to remember them correctly.
The amount of knowledge in the world is great, and each person is interested in something.
So to learn what you are interested in is your purpose!