Ammon had correctly perceived that Lamoni needed to know that Ammon was just a man. This was confirmed when Lamoni finally spoke, and asked the question that formed his greatest fear: Was Ammon the Great Spirit? What is added was the idea that the Great Spirit would know all things. This becomes important as the conversation continues.
Ammon assuages the king’s fears. He is not the Great Spirit. That, of course, leaves open the question of how he has done things that it would be assumed only a semidivine being could do. Those issues come in the next verses.