A point is a place that has no continuation; a ray has a beginning and then continues on into infinity. But a line has no beginning and no end: it is effectively everlasting, eternal.
If the soul is eternal, then must it not also exist before birth as well as after death?
And if the soul was before birth, then why should it have been born at all? What reason might there be for taking a soul, thrusting it into a body, and subjecting it to all the physical, emotional, and spiritual pain that this world has to offer?
As well might ask why we must be born at all and not simply spring full-grown from our parents' heads as did Athena....
But born we are, and this separates us from some forms of life that slowly bud instead, as coral, and do not separate from the adult until fully-grown. I think that this is due to our complexity: we cannot know until we experience, and so we must take a time to grow after birth. But for a time, when we are growing, we are too fragile to live in the outside world, and so we are kept safe in our mother's womb - and yet even there we may be harmed, by drugs or improper diets or physical maltreatment or any host of other things, so that as we continue our growth we are stunted and unable to reach our full adult potential. And then, once we are born, the choices we make and the guidance we receive may either heal or harm us, free us or kill us, when we reach for our adult life.
Perhaps our time before birth is our time in the womb, and our physical birth our spiritual one as well. Then perhaps our life here is our childhood, and death only the last rite of passage into the adult life where potential may be fully realised: then the pathos of this world would be seen, also, for the wrong choices, the wrong behaviors, might cripple us as adults even as they cripple children in the physical world's realm...