What? Vastaya most certainly are not humans. Vastaya is a category full of sentient creatures (multiple different species) with animalistic features, from straight up anthro animals like the otter people, to mix-matches of a bunch of animal features like the chimera that we first see, to humanoids with a few animal features (Ahri), to straight-up shapeshifters like the pig merchant.
Like people have said below, Ahri was never referred in-universe as a kitsune or gumiho. She was clearly based on one, yes, but it seemed like it wasn't a thing that existed in Runeterra, and it seems like it doesn't exist in new Runeterra either.