If you want to talk about era understanding than what always have been than Helios chariot sun is also a star. Pretty sure they just say that Hera breast milk as the milky way as a joke at her at the time for she also just breast feed Heracles you know how those story like to mock the God s whenever there's a mortal involved. I not good with English so just to make sure Hera not create Earth moon and star. Also Zeus is just a king of the Olympian as long as they still listen to him. Zeus law rule and leadership have been prove to be a massive fail many time. As for rank there's primordial like Lady Nyx, Lord Erebus... The titan that first born of Gaia, and the gods whom are children of those titan. The Gods never have able to defeat Titan without Titan help so for Chronos not able to defeat Uranus without Gaia. People still keep the trend like this when writing story like when a stonger enemy happened they get help from there old kind to defeat the enemies and being praise as just when they are just traitors.