Pre-existent Souls?

Source: A.A. Long, "Roman Philosophy," The Cambridge Companion to Greek and Roman Philosophy, ed. David Sedley (Cambridge: Cambridge University Press, 2003) 210.

"Tertullian in his work On the Soul draws heavily on Stoicism, aligning himself against Plato with the Stoics' identification of the soul with 'breath' and also with that school's doctrine that the soul originates at birth."

Did we pre-exist? That's something I've always wondered. Suppose I were not born to my parents, either because they didn't meet or the James Pate sperm didn't make it to my mom's egg. Would my soul be someplace else? Because I have an elevated sense of my own importance (unfortunately), I'd like to think I'm not the product of chance or other people's decisions.

Plato believed that the soul is immortal, meaning it pre-existed our birth and survives our death. He talks about this in Phaedo and the Republic. But the Stoics apparently maintained that our existence originated at birth, and the Christian father Tertullian picked that up. I wonder what other Christians thought about this issue.

What's the Bible say about this? The King James Version of Ecclesiastes 12:7 states that "the spirit shall return unto God who gave it." Is the spirit the soul? Or is it the breath of life, which God gave to each human being when he animated him or her in the womb? Maybe it can be either one.

In either case, God is intimately involved in our creation, meaning we're not accidents, whether our souls pre-existed our births or not.