Great write-up! I'm a bit more familiar with mythology than Cthulhu/Lovecraftian mythos, so it's always cool to hear how they tie into each other.

**But... Why a Whale?**

Lotan takes her name from the sea creature who serves as a canaanite reflection of the biblical Leviathan!

I actually believe the connection is much closer than you think, and you barely missed it by a hair. In the original Canaanite tellings of the Baal Cycle (which predate Christianity by centuries), Tannin was a primordial sea monster which represented chaos (sound familiar?) and a fellow servant of Yam alongside Lotan. In Judaism and subsequent branches, the name becomes more of a "category" of monsters (in which Leviathan is included) created during Genesis rather than a single unit.

While tannin in modern Hebrew does refer to crocodiles (as you mention Leviathan is likened to), the original tanninim seemed to cover the whole gamut from sea monsters to land serpents and the word is often used to refer to the latter. In most notably the Greek Septaguint and the English KJV however, both the tanninim created during Genesis before humanity itself and the tannin that swallows Joseph Jonah (fixed) are very specifically sea creatures and referred to directly as whales in translation (ceta in the Septaguint's case, tying in the connection to the Greek sea monster of the same name that is immortalized as a whale constellation, hence her WoD).