Beautiful question, ananceleste. I wish I had seen this one 18 months ago.
First of all, we have to clear up what is meant by "spirits."
God created us in His image and likeness, but He is not Homo sapiens. That means that we are immortal, non-physical, but spiritual sources of creation.
Reality Check: Genesis 3 tells us that we took a wrong turn. "Adam" and "Eve" are symbols for us -- the fallen ones.
What does it mean to be a fallen one? It means that we cannot see without physical eyes. It means that we are separate from one another. It means that we are trapped in the false self known in Buddhism as "ego."
I have seen the Buddhist paramitas that give rise to miracles. I have understood the mechanics of creation woven into Genesis 1 and 2. I have seen without physical eyes for the first time in countless ages, but only for a moment some 42 years ago. I saw that I was not casting a shadow on the evening wall of the second story where my body still sat.
Spirits are those who have not yet awakened as spiritual beings. They are still caught separate from the whole. They are without sufficient love. They have not yet taken complete responsibility for their condition. And they have not yet accepted the 100% confidence that allows them to bend or break the laws of physical reality.
When we let ego go, and regain our love, we merge with the whole (God) once again and can see without human eyes. We will then have continuity of consciousness without the need for human brains.