God has planned that we be made in His own image, meaning according to His design. Everything in Creation is predestined but that does not exclude the God-given ability for us to make choices. We exist as what we are, who we are, and when we are because of
Creative Momentum.
One of the many features of Creation is motion.
The Universe has location, organisation, space, time (or spacetime), energy, matter, velocity, and life to name some of its well studied components, and all these are involved in motion, including ourselves.
We are who we are because of the creative process God has set in motion. Our exact moment of conception is the result of
"creative momentum" which means any alternative conception results in an alternative person being created, one who would not be us.
We are who we are because we are not who we aren't, just as God knew it would be before the beginning of time..
Psa 139:13-16 For You formed my inward parts; You covered me in my mother's womb. (14) I will praise You, for I am fearfully and wonderfully made; Marvelous are Your works, And that my soul knows very well. (15) My frame was not hidden from You, When I was made in secret, And skillfully wrought in the lowest parts of the earth. (16) Your eyes saw my substance, being yet unformed. And in Your book they all were written, The days fashioned for me, When as yet there were none of them.