In this statement I am not addressing the idea that there are certain myth archetypes, a la Frazer. I find archetypes useful for discerning when a story has become a myth, but that's all the further I care to push that set of ideas.
Well, if you wish to ignore the entire last century of mythological thought, which, from a variety of perspectives (the myth-and-ritual school of cultural anthropology, psychoanalysis, structuralism, comparative religion, etc), explores myths as a narrative expression of deep-rooted psychological, philosophical, and cultural concerns and habits of thought, so that you can focus on it as a kind of politicized, ideological community-building, that's your prerogative.
I find that's a bit too cynical for my taste, even for a 'realistic' world like Harn.
Don't get me wrong-- I'm not saying that the kind of politicized interpretation/reinterpretation that you describe isn't real, or part of the reality of myth. Of course it is. But to suggest that myths "only really exist" in such a context... no, that's too limiting and shallow. It turns myth into nothing more than propaganda.
So when presented with a myth like that of Naveh and Halea, my first instinct is to think, "What community would tell this story, and why?" The meaning may be completely obscure in the TR720 context - the community and context in which the myth was created may be long gone. In this case, is seems plausible that a Halean community composed the original story to demonize a Navehan community, and a cursory scan through Venarive finds a reasonable candidate in the Karejians who were threatened by an expanding Dalkesh Empire in the Second Century TR. It is obviously only a theory, but that's the fun part about this sort of conjecture - you are rarely ever proven wrong.
True, very true. And, I'm sure you can even find a way to get around the inconvenient fact that the Halean church hadn't even been founded in the 2nd century.... which would make Halea a most unusual choice to include there.
But even so, I would then ask the question(s): What is it in this *original* meaning of the story that would possibly appeal to 8th century Harnians? What do they see in it, that they even bother to retell it? Whatever the original meaning of the story was to the supposed Karejian author who told it, it seems to me, it can't be the one that matter's today's Harnians, who have now integrated this story into their own shared mythology and see it a totally different context from the originary one that you posit.
Some of the myths are relatively obvious. The Agrik/Larani relationship describes two faith communities at odds with each other - the demonization of the "other", and it also describes the virtues and vices of each side (at least, in the versions that each faith maintains). But some parts are obscure. Why does Ilvir appear? What community inserted him into the story, and why?
I would say that that reading the Khamar / Sunder Claw myth, as part of a a set of concerns about about life, fertility, etc. provides a range of possible answers. So does looking at the structure of the stories. Ilvir in these tales, stands in a weird kind of relationship to Agrik-- essentially as a kind of 'mate', as it's through this ironic coming together of the two of them (Ilvir the infertile breeder of life and the symbolically castrated Agrik) that the V'hir (and the Ivashu) are born. (I've often thought that Ilvir breeding the V'hir from Agrik's fallen blood was reminiscent of the blood/semen from Uranus' severed genitals giving birth to Aphrodite in Greek mythology... but that's another story.)
At the same time, the presence of Ilvir in these two tales seems strangely related to the equally odd presence of Peoni-- and there's a curious inverse relationship there too. At first, the tale of Khamar tells us, Agrik nearly slew Larani-- but Peoni healed her. Then Larani wounded Agrik-- Peoni offered to heal him. He refuse her offer but instead takes up Ilvir's offer instead. This suggests, in a weird kind of way, that the Agrik-Ilvir relationship mirrors Larani-Peoni one. This seems rather fitting as both are relationships between war gods and fertility gods (or in Ilvir's case, life without fertility). There seems to be me be a kind of 'structural logic' working here that suggests a pattern of mythic thought that's connecting war, infertility, life, and healing in some abstract way. (I'm tempted to try and draw out some Levi-Straus style triangles to work this out, but I don't think that's going to happen....)
Here's another two-penny theory. The idea that Ilvir needs Agrik's claw to create his Ivashu is a sort of emasculation of the deity. I imagine that an Agrikan community - either missionaries or conquerors, or both - encountered a Ilviran community (probably the Jarind around the Sea of Ivae), and wanted to delegitimize the Ilviran faith. In this part of the myth, Ilvir is reduced to a secondary power - he can only create because he has a piece of Agrik. The Larani myth can't be much older than BT300, so the period between BT300 and TR1 would fit. The two communities had to be in close contact for a long period of time, since the Ilvirans apparently turned the myth back around and made Agrik's V'hir the creations of Ilvir - thus putting Ilvir back on par with Agrik.
Also possible, sure.
I've got to step out but your last two paragraphs are also really interesting. Hope to get to them later.