In Verdict, a true Mythos- much moreso, a true Creation Mythos- is very difficult to nail down, at least from the perspective of humanity. No one really knows how the universe came to be, exactly, and there's even less understood about what might've done it in the first place. Regardless, humans love to wonder, and the humans of the Old World are no different. There are numerous theories as to what began it all, and, more than that, there are many practices to worship, or at least revere, aspects of said beginning. This page will review both the Creation Mythos as well as the worship of evidence of said Mythos.
Creation & Worship
As mentioned above, very little is truly understood about creation. What humans have settled upon, though, is that Spirits played a great role somewhere along the line. The general consensus is that the Spirits present in humanity's current era are descendants of the Creator, whoever that was, and that the five Elemental Planes- six, if you include Limbo- are representative of pieces of the Creator. As such, most humans will pray to or worship said descendants, typically their given race's Patron Spirit, as a way of paying respects to that lineage of creation.
Mages and Weavers, while still paying respects as mentioned above, will sometimes attribute their thanks, prayers, or even sacrifice to the Elemental Planes instead. More specifically, they will do so to their chosen Plane, provided they've selected one element to utilize as a "primary", of sorts. While it is well understood that these Planes are not sentient whatsoever, nor coherent or even living, the practice is maintained; the Planes are viewed as intentional creations of the Creator, and, in a sense, are thusly very similar to humanity themselves. And, of course, each Elemental Plane is parent to an element, so it doesn't hurt to thank your chief magical tool once in a while.
The largest sources of Spirit worship are undoubtedly the Patron Spirits. They are few in number, and only four are well-known. However, those four are so prominent in human society that they alone elevate Spirit worship considerably. Their revered status has spilled over to not just Greater Spirits, but Lesser Spirits, too. Many humans consider it bad luck to cross a Sprite's domain, and some will live life with good intentions for the sole purpose of evading Spiritual "karma"; a concept perpetuated by the Lesser Spirits' desires to protect their domains from litterers and vandals.
Of course, races do not worship all Patron Spirits equally, and some even despise an opposing race's respective Patron. There's also much conflict over what to name them, and it's rare for a race to see eye-to-eye with the other three on how their Patron should best be perceived. In fact, most modern understandings of Spirits and creation only exist due to Aiphe spreading knowledge to each of the other three. This limitation is often perceived as a representation of the four Patron Spirits' wills, and those four Spirits are often viewed as a personification of said behavior.
The limited records detailing encounters with the four Patron Spirits seem to back up this belief. Each is personable in its own way, with tensions and pitfalls all the same.