@DragonParadox
What does Viserys think of this theory:
The Fourteen have High Valyrian names, rather than Draconic (or Primordial) ones. This is because each of the Fourteen are actually Dragonblooded Sorcerers who ascended into True Dragons, who then proceeded to ascend into actual Deities.
This makes more sense linguistically because the Valyrian deity names actually seem a little more archaic than the names the Targaryens often leaned on. Syrax vs Daenor, Balerion vs Aenys, Meraxes vs Aenar.
Sub-theory: The Fourteen Volcanos were the center of powerful leylines or other magical nexuses. Much like how the Wall is such a concentrated source of magical power that people living right next to it are more likely to become empowered or be born empowered, or have their inherent bloodline awakened, the Valyrians were noted as having more sorcery in their society, especially in the Heartland, because they lived right next to something like the Wall.
It would certainly make sense in that the early Freehold made damn sure to kill or enslave all the true dragons they could find and even wipe their memory from existence. Given this the thought of them worshiping dragons is very unlikely... but not impossible given the cunning of dragons.