Honestly, all I can say is God creates life. And human beings have souls. I however cannot say for certainty if the soul is attached to the body at the moment of conception, thereby giving it life or if it comes in a couple of weeks later. I have to read what the theologians or saints have said about it. As for animals having souls, I do not think so ( I am sorry if I wrote up there as if it was fact, its just my opinion) because I believe what sets us humans apart from animals is that we have a soul (since we were created in God’s image) while animals dont. If we were to assume animals have souls, then it is also safe to assume bacteria or unicellular organisms have souls. That is a little far fetched in my opinion.
My position on the topic is all men born of a woman have souls, God gives life to animals and plants too but these may not have souls and what sets man apart from the animal, plant or unicellular organism is that man is created in the image of God, and does havw spirit/soul.