This is the best explanation of the ego I have heard so far. The first three components: "I am what I have"; "I am what I do"; and, "I am what people think of me" are the "self" components. They are, I believe, the basis of what makes a human animal a person. In other words, they are what separate human beings from animals. The other three components of the ego: "I am separate from others"; "I am separate from what's missing in my life"; and, "I am separate from God" are the autonomous components, the ideas that individualize us and make us autonomous individuals. Ergo, the ego makes one a "separate self". Does it serve a purpose? Perhaps. I'm no expert and just beginning to learn more about it, but I believe it's what helps us form our own identities and perhaps, the human ego is self-preservation mechanism or a device used to protect our vulnerable inner cores and feelings. Maybe??
Don't Ignore a Weimaraner -
Where is that fountainhead?
The greatest lie ever told The Holocaust