It is not that the body has the soul but that the soul has a human experience. The spiritual world was created long before the material world. The spiritual world is very complex and has an infinite number of levels. The material world was created by the spirits for them to learn and to grow. We are those spirits who came to Earth and temporarily forgot our spiritual nature. At least many of us forgot. The essence of an Earth experience is to live a life in forgetfulness not having solid proof of our spiritual nature.
This experience is very invigorating for the spirits since they can obtain an experience of being lonely, being in charge of their own destiny, thus re-living the experience of God - being the Creator. Compared to other planets, the experience on Earth is very unique - the majority of other civilizations don't forget their spiritual origins and therefore the experience of loneliness is not that strong. Also they are not as afraid of death since they understand that there is life after death. Thus, the Earth is one of the toughest study courses in the creation. Although it is tough, it became a place where life and beauty are experienced by spirits, while strongly providing better opportunities for growth.