I just do not share your definition of "inhuman". Gorillas are not humans, chimps are not humans, dogs are not humans. Yet they are not incomprehensible to us, they are not completely unlike us, they are no xenomorphs. Your definition of "humanity" would entail a large section of the animal kingdom. I just don't think that is a coherent or helpful definition.
Here is the point; think of a story or book or movie where dogs are
characters. Not actual dogs, but dogs in fiction. What comes first?
Homeward Bound, maybe?
All Dogs Go To Heaven, if you're a Bakshi fan (and why wouldn't you be?). The thing is, those
characters.... are human. Not in the literal physical sense but in the metaphorical, literary sense. They are human because we*, writing them, are also human, and are reflecting aspects of our humanity onto them. The fiction we create... it's all through a human lens. And that's what I at least suspect (I can't speak for her) that's what she's talking about.
The thing is, pretty much all non-human
characters fall into this category. Sometimes by accident, but often by design; the entire purpose of fiction to explore the human condition, through whatever molds and lenses that may interest us at the time.
That's not to say that true xenofiction is impossible, it's just, if you're telling stories that have nothing to say about humanity or the human condition...... why?
*Or I guess in at least one of these examples, Ralph is human. Presumably