I ran a short campaign in the Star Fox universe where humans were rare because they were created by Andross as ascended monkey people.
I plan on a future campaign set in the Metroid universe that's about someone who uncovers Andross's research and early human history.
I regrettably ran the first game in hacked Starfinder. I think Albedo would have been better for my purposes.
You could also try doing something similar with Ironclaw if you don't mind the fur. Furry systems really focus on the difference between species, which would really make you think about what makes a human, human rather than just generic baseline race.