Why were ancient Olympic games held in honor of Zeus?

The main reason they did that was one of the ways they showed loyalty to the their gods, and Zeus, being the King of the Gods, but I am pretty sure that they wanted something to symbolize higher power then just a simple statue or temples. So the Olympic games took place as a sort of a mass symbolizing importance. As a matter of fact, their was an Ivory and Gold statue of Zeus in Olympia. Hope that helps.