Consciousness is not an illusion, it is a real phenomenon that is experienced daily by almost every human. You might be referring to free will and its subjective experience, which is a different story.
Unless you believe in supranatural explanations for it, yes, it does. The beliefs you mention, like a flat Earth, were/are real and also false. So in this analogy, consciousness is real, but many of the explanations for it or powers ascribed to it are false.