A ship has a captain, a country has a president, and a company has a chief executive officer. Experience has shown that even large complex organizations run best with a single person at the helm.
There is a structure and organization within my church as well, and in many cases it uses the same model listed above, but these are not Biblical offices. The Biblical concept is one of a body with a head, and I am jealous of the position of the head that only I can fulfill. Those who serve me in any capacity should be aware that they too are under authority. For my body to function in a coordinated and effective manner is a testimony to me as the head of my church.