In the material world, everyone has a body with its fulfillments. We are separated from each other by biological bodies, and psychologically, each of us perceives themselves as an individual personality.
In spirituality, everything is constantly changing by going from one state to another; the Light and the vessel are always different. We “clothe” in a certain state and name ourselves in accordance with it as actors who change costumes for new roles. It is as if we are in a science fiction movie where we play a variety of characters.
There is no such notion as a “private, permanent soul” that exists autonomously, climbs the ladder, and preserves its individuality. It’s hard for us to understand how our "self" disappears. For example, it is said in the article “600,000 Souls” that each person who corrects his soul will uncover Malchut to the world and will be named King David.
From the 4th part of the Daily Kabbalah Lesson 9/26/10, "600,000 Souls"