I agree with you that the little tales in the leaks do actually fit the style of real mythology, which is full of stories about freaky sex from incest to bestiality to tree-sired pregnancies and self-cest.

Imo this is just an example of why these attempts at story-driven immortal franchises will inevitably collapse under their own weight. Pokemon initially worked fine as a sort of amusement park reality where there isn't really any focus on the wider world or its history, but as these weird amalgamated corporate franchises get bigger than their original scope, they run out of material to grow up with, and they start to just grow in every other direction instead. It's why your favorite Netflix series starts to fill its runtime with episodes devoted to giving every side character, no matter how irrelevant, a full developmental arc--the "universification" of settings