You are the universe simulating a brief experience called human
Hello, who are you?
Erm, I'm Matthew, I'm 28, I...
Stop playing around, who are you really?
image sourced from https://www.forbes.com/sites/startswithabang/2016/01/23/ask-ethan-is-the-universe-itself-alive/
On the left is an image of a 'neuron and connections in the brain'.
On the right is an image of the 'large scale structure of the universe'.
What you really are was NEVER inside the box. And Socrates said:
The only true wisdom is in knowing you know nothing
See also: The universe is not physical