The Torah seems to at first to favor the idea of one powerful leader, Moses, who has direct contact with God. In the ancient world of the Middle East, the King tended to be the god. He combined temporal with religious authority. But despite Moses’s special relationship it was Aaron who became the High Priest and divided the roles.
After Moses Joshua initiated period in which God only rules and different judges from the tribes emerged simply as temporary leaders who fought God’s battles. They refused the kingship when it was offered. The last Judge Samuel wanted his children to succeed him but the people refused and asked for a king. They echoed the statement in this week’s Torah that “If you say you want to appoint a king to be like the other nations, you may appoint a king whom God chooses.” Samuel responds negatively. He echoes Moses’s defense when challenged by Korah “Have I ever taken anything for myself?” Even so God approves of the idea even though “being like all the other nations” is the last thing God wants.
The Torah seems to approve the idea of a king, not as a god, nor as a religious leader. But rather an example amongst many of a possible political ruler open to be modeled on roles popular beyond Judaism. It is a charter for options, alternatives, whatever the other nations are up to, whether it is king, or president, or prime minister or even benevolent dictator. Circumstances are allowed to determine the best form of rule for that era. The only condition is that whoever the ruler, he or she must accept the authority of Torah, of the Constitution.
If we take all this together with the roles of the hereditary priesthood, the charismatic prophet (who was not appointed by anyone and it was a position open to women too) , or the meritocratic rabbinate, we can see how brilliantly the Torah introduced systems that were current then but gave us the flexibility to adapt and choose which one would be most suitable to our present condition. And over history we have been governed by all of these alternatives at one time or another. Even the constitution would be able to develop from within to meet new challenges. But still loyalty to the values of Torah was the one immovable principle, regardless of whichever system we might adopt.