Right... we are just colonies of cells which behave in programmed ways to generate predictable responses from other cells in other parts of the colony who have their own jobs to perform in maintaining the homeostasis of the colony. The illusion of self is useful because it ensures that the collection of cells entrusted with executive functions act in the interest of the entire colony by perceiving it as a unified whole.

Another way to put it: the experience is real, but it might be misleading.

A hallucination is an experience of something that doesn't exist, but the experience itself does.

Misleading in some respects, but overall helpful. Like a computer desktop.