I think our soul existed in the mind of God until we were born... thus conceived before we were formed. I do not believe that is to say that we literally existed, or had any form of free-thought or 'history' before we were born... only that God knew about what we would be like when He DID form us in the womb.
Since we are engaging in idle speculations,
mine is
that we did exist in identifiable form of some sort outside the 'mere' mind of God--as though anything about God could be 'mere.'
Certainly God COULD have had it as you say. It just doesn't fit His Nature and character as I read Him.
Interestingly, a friend of mine postulated that After all our earthly choices are concluded and God has entered all the data in His heavenly computer, there would be no further need for us to exist in our heavenly body form. I think, that, too is quite askew from God's Nature and way of doing things.
I do NOT construe all reality as some elaborate version of THE MATRIX.