The Singarthans were apparently one of the races conquered (or subjugated) by Yahssremore pre-Elorii (as they wanted to use the Trolls as il'Huan fodder), and likely their current form is a modified version of their previous one as part of an effort into making them into the magic bullet the Ssethrics wanted/needed.

The Celestial Giants (Jotun?) are from another plane/planet from which it appears the Pantheon of Man has little or no power, and the Dwarves are simply a batch of those who are within Illiir's realm.

My understanding is that the Celestial Giants moved between the worlds using world gates, staying ahead of the dying of worlds. There is a mention to their "ancient enemy" at one point. Something I thought might mean entropy. The idea being that they, like Menatas, just don't stick around when a world starts to fall to entropy, they just flee off to another world.

Interestingly, while they had apparently noticed the voiceless one on other worlds they lived on, they had never considered them an issue - like rats. It makes me think that on most worlds the voiceless ones are the precursors to something even bigger, but on ours those bigger things are held back by the God's war on entropy. Thus giving as a piddling little threat like the VO to deal with...

So it sounded like a bunch of them came to Onara and ran made the deal with the PoM, but others on other planes are still Celestial Giants, instead of dwarves. Considering their gates apparently require a divine element to use, it makes me wonder who (or if) they worshipped before becoming dwarves and worshipping the PoM. The other remaining giants on Onara all seem to worship the PoM.

Yes, we know nothing about the Gar faith, their gods, or their creation. Same with trolls, early man, etc. We've met other races that at some time in their life have worshipped the PoM, but which we have no idea about their creation. We believe that there were once many more gods (for the dead races the Ssethrics destroyed) so some of them may have had creator dieties as well. But it seems clear we don't have a good handle on how many races were created, since creating life does seem to be a major power not all gods are gifted with.

Can you cite your source of this as I am not familiar with any reference to the CGs being refugees of the silence or any tie between them and the VOs

I don't have my books to check. As I recall the references were oblique, as I mentioned. I think I am taking two different comments from different locations and putting them together

1. They had noticed the VO on other worlds, but just considered them vermin. Not a threat to them.
2. They moved between worlds staying ahead of "an ancient enemy"

So there is no direct relationship. I was inferring a connection, and indicating that normally, the VO didn't seem to be a big issue. Since the VO seem to be a big issue on Onara, I am inferring that something is happening to keep an even bigger issue from happening. These easily all be wrong inferences.

Yes. Uromah, the Fallen Honor of Cadic was last seen fighting off entropic monsters that were "erasing" the world of the Fihali. I'm pretty sure those are the "bigger issue" that needs to be held off. I believe their proper name is "Soldiers of Oblivion." Part of the PoM's game plan has to be keeping them from Arcanis.

I hadn't thought of this before but I think one of the stronger arguments against Umor being connected to the Silence is that he doesn't appear to have VO or other creepy crawlies among his followers and servants. Neither the human nor the elorii accounts mention anything remotely like them.

I assume there are other gods that also have created life. But they aren't around to tell the tale. If the Ssethrics are right that their wars of extinction also involved their gods consuming the essence of the other species gods then there is potentially a cosmic game of King of the Hill going on and a lot of losers have lost their chance to share their commandments.

I have always thought that Belisarda was essentially a primal spirit scaled up to a planetary level. She is the manifestation of the life force of the world. Her unique deity Cant, Crushing Weight, doesn't work on other worlds. Presumably because she's not the Life/Planet goddess of other worlds. It stands to reason that each Mortal world has a similar Deity to Belisarda who should be able to create lives and souls.

I had originally assumed that the reference to the Giants' "ancient enemy" meant the Dragons. Perhaps it is a reference to Entropy.

(aside: could there be a connection between dragons and entropy?)

I'm been reading this thread with great interest.
I'd like to put in a few ideas that some people may have forgotten.

val Holryn's OP talk about the theory that Umor is Kassegore.
And others mention that it was claimed Umor killed "the gentlest of the PoM"

Well Ssethregore: In the Coils of the Serpent Empire states that after Kassegore's vision of the future, BOTH Kassegore and Yig left.
So expanding on the theory that val Holryn mentioned, what if the events when something like this.
Kassegore has the vision of the future. The enemy of his people being the VO, who the Ssethrics fought since finding the Lavender Way. Yig and him decide to bring the PoM here to ensure that the human allies come to Arcanis. They leave together. Kassegore talks with the PoM. Yig is hidden and she kills the gentlest of the PoM, so she can appear as one of the PoM later. I always found it odd she could create Vals like the Valinor could.
Kassegore gets blamed (as per plan) and runs back home with Yig.
No time for Stage 2.
For the Lesser Gods is really helpful here. Umor is called the Celestial Dragon, and his symbol is a dragon in the shape of the infinity symbol biting it's own tail. Well Kassegore's symbol is a dragon in a loop biting his own tail. Umor speaks with Belisarda convinces her of his plan, and hides her from the PoM. You know, no where does it say that the Elemental Lords every met Kassegore, so it makes sense that none of them recognized him. And even have they had met, Yig is the master of trickery and deception she could have disguised him. Anshar appears tells the PoM of the ability to absorb other deities for the greater good. The final battles begins, Umor is cut in half
Cadic traps one half inside the back moon, and "a green goddess" Yig, places the other half in a chasm.
And everything is exactly as it should be.
The Ssethrics legends have been met. Kassegore is "asleep" Yig is free but away (with the PoM)
The Elorii have Belisarda working on Kassegore's plan while in hiding. If others (like the Silence) think she is dead then they can't find her to kill her in truth.
The PoM has begun their journey to save humanity with Yig (secretly?) among them to keep them focused on the goal.

Who are the humans that came with Umor, how about Yissera? Or what about real humans that loyally followed Kassegore back from wherever the PoM actually come from.
Why is the moon so important to the Silence, because Kassegore is a threat and half of him is trapped in that moon weakened. They didn't blow up the moon to free him, but to kill him.

I believe a big theme in Arcanis is the importance of putting aside differences that exist among every race and working together for the greater good. I have always felt that is what the big final show downs are all about. Every race brings something valuable to the table. And working as a team we can conquer any epic threat like Manetas, or Uhxbractit.

Another interesting note for the previous post: Take a look at the adventure "Wrong Turn at Coryan". Apparently the Ssethric rune for Kassagore could possibly be mis-interpreted as the Elorii Rune for Keleos. Not sure how relevant or canon it is (let's face it, if Henry didn't write the mod there is a chance that what is in the adventure isn't QUITE correct), but it is an interesting piece of information