That Jupiter could be seen as a king is not so strange for out modern eyes, as we know how immense this planet is. Nearly big enough to have been a sun.

And Jupiter has 4 big moons, giving a signal that he is part of our middle world. Could the ancients have seen these 4 moons?

Saturn must be older (and therefore wiser) than Jupiter, because Saturn moves slower; has a longer period of revolution around the sun.

In the beginning there was only sky and water. Our middle section of cosmos was created later. Saturn - if king - must be king of the watery world. Water always runs downwards, i.e. to the Under World.

These two kings, Saturn and Jupiter cooperate and have a meeting (conjunction) every 20 years.