Point to one verse claiming a soul is non-existent, even in sheol.
You do not get your ideas from Scripture. Samuel was called up out of sheol. 1 Samuel 28.
Was it actually Samuel or a demonic ruse? Notice that Samuel didn't identify himself. Saul assumed it was Samuel. The woman said that she saw a divine being coming up from the earth. How did she know it was a divine being? I don't know. I've never seen one. (Remember, Satan can appear as an angel of light.) A lot of assumptions were being made that day.
The woman described an old man with a robe. How does she see him unless he has a body? Or did she see a spirit that only appeared to be Samuel?
There are so many questions that I have about that passage. My only point of reference that might possibly inform me of what might be happening is the Transfiguration of Jesus, where he and two disciples witnessed the appearance of Moses and Elijah.
Maybe Samuel didn't actually come out of the grave. Maybe Samuel was seen in his glorified state, just as Moses and Elijah were. That would explain why the woman thinks she saw a "divine" being.
I don't know. All I know is that a "soul" is the unification of body and spirit. Once the body dies, the soul is destroyed, unless, as Jesus asked the Father, "keep my spirit."