I leave my suspension of disbelief squarely at the door, Christopher. For me, any answer for "Why so many human-like aliens" is that Star Trek's interaction with them is about our interaction with ourselves and different cultures. But yes, you're right they're not LITERAL griffons--which I'd be equally okay with.
Glad you liked my review.
You should write more novellas, this was quite good! I really hope we'll see some Kinshaya-Federation action soon.