Who was I before I was born, who was I when I was born, who was I when I grew up, and who was I when I slept? What does this mean?

Who was I before I was born: If my parents didn't give birth to you, who are you now? Who was I when I was born? Who were you when my parents gave birth to you? When I grow up, I finally have my own thoughts. Close your eyes. Who is it? What shape do you have in mind? It's better not to come or go. It's like you have never been born or died in this world, so you can walk on the earth once. This poem is very Zen ... how to understand it is up to you. I'm just a translator.