And a response to his question: what did God do?
Well, I would say I believe what Scripture says. He did it all:
Colosians 1:19. “For in him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things have been created through him and for him.”
How much was was by primary cause? How much was by secondary cause?
Proverbs 25:2. “It is the glory of God to conceal a matter; to search out a matter is the glory of kings.”
I know He did it all. How much did creation do on its one? I do not know because the Bible does not tell me. I’m sure this will be a frustrating answer to you, but I do not know how to speak with confidence about God’s action independent of what He reveals to us in Jesus and in Scripture.