OK, that was my last post about gods and DS. I don't think it is really relevant to what
@Yaarel is trying to do.
Its relevant because Yaarel is trying to shape a setting, so it is helpful to have discussion on the divinities that may or may not exist.
For me, I think if we're trying to keep a 5E canon game, that means that Athas-Fyreen was once part of the First World. A long, long time ago. A long time ago. When the First World shatters into a thousand-thousand different wildspace systems seperated by the gush of the Astral Sea, the qualities we associate with these settings finally take form. Athas-Fyreen and Doomspace were, canonically, protected by the Primordials there who used a gas giant to create the Crystal Sphere around the wildspace system. Then, as time passed, the people of Athas-Fyreen discovered Defiling, and it was all down hill from there.
Whether there are gods or not is ultimately up for each DM to decide, including you Yaarel, and there is no right answer. I could just as easily make the argument that the soon-to-become Athasians of the First World did worship gods, since the poem states that gods introduced mortals to that world. You could take the angle of, after the shattering, some of those gods followed the Athasians to their Wildpace system, or that the lost temples and what-not are relics of the first world, or that the lost temples were made to honor heroes or primordials or cosmic forces once forgotten. The reason Dark Sun gives no answer is because giving an answer takes away part of the fun a DM has when interacting with a setting, which is applying their own tastes to it to make it their own.
For my Dead Sun game, the gods indeed were kept out by the Crystal Sphere created from the gas giant. Those gods did break the sphere, and then they demanded worship from the two worlds of the system. Neither gave them their worship, and the Dead Sun was created. These gods might not have created the Dead Sun (in fact, in my version, they def did not), but they certainly didn't help the people after it was made either. This lens is every bit as valid as there having been no gods and you running Athas-Fyreen
@Yaarel as purely based off the primordials/elements, and going the full nonthiestic route. You cannot make a strong enough argument to go either direction beyond taste and vision.
That being said, I love the nonthiestic ideas for the elements you have presented. They have inspired me. Zariel and the Violet Flame have influenced Fire worship, the Raven Queen has influenced water worship (now ice), the Pale Night has influenced earth worship (for the gold, stardust deserts covering the worlds), and Celestian has influenced air worship. These powers are not worshipped themselves, but their imagery and what they have done in the post-Dead Sun Doomspace has warped the elemental mysticism across the setting. For example, where once water was flowing change, life giving, destructive and stormy but so desperately needed, now it is ice, cold, a stillness punctuated by blizzards that hides villains and weakens heroes. Water Clerics do their rituals and supplications now to keep the element at bay, to push away blizzards, to prevent the cold land from killing them outright. So, thanks Yaarel for that bit of inspiration, it helped!