A quick googling tells me Belit and Valeria are much closer in body type to classically feminine. I would peg them as DEX fighters (in 5E terms). Crucially, they look nothing like the muscle mountains I associate with 20 STR 20 CON.
Yeah, if I was running 1e up to even 3e I'd likely follow your POV. I remember playing 3e and keeping my female Fighter PC's STR to 16.
4e-5e, I ceased believing that the D&D STR stat had anything much to do with actual visible musculature, so when a 5e player of mine rolled up an Atlantean noblewoman with STR 18 I just described her as Brigitte Nielsen type, not Hulk-type.
I'm much the same with INT stat, I don't think it has much to do with actual intelligence.
Edit: However in practice, many of the Belit type NPCs IMCs are DEX-based Finesse fighters with moderate STR, just as you say.