Yeah, that's why it's important not to deal in absolutes here, the boundaries are definitely fuzzy and you can historicise/euhemerise myth anyway, as you wrote. I'd say that mythological film's got to have explicit divine/supernatural involvement (but I'm still pondering this).

Absolutely. Also there is this. Which I'm only sharing because I've just discovered this poster and film.

My own layman’s interpretation of this , is that Roman myth doesn’t really have anything that Greek myth doesn’t do better or more detailed ? Like for most people the myths are similar enough that it’s mostly just name swapping and in that case why not just go with the Greek version?