By 'keeping humans as pets' do you mean other racse literally keep humans in cages like animals, or more like how some parent s treat their children as pets (disregarding their opinion, forcing their wants and desires upon them, just generally not viewing them as an equal or even a separate/sentient entity with their own thoughts and desires)
It kind of depends
Yes in some cases humans are kept in cages like circus animals
Or put in a type of zoo
Some REALLY rich folks actually have a human as a pampered kind of pet with cushy living quarters and a whole staff to spoil and pamper them.
You have a few who see them as nothing but dumb animals, but a majority of people see them kind of how humans see chimpanzees and other monkey species. Very intelligent compared to other animals, but not quite to the intelligence level they consider themselves to be. So it really kind of varies from case to case, but its honestly so extremely rare to see a human because the earth is considered a protected planet. The only way you see a human out there in the universe is usually the result of poaching
A couple of humans have made their mark in intergalactic history though. One is even remembered as one of the greatest commanders in history during the astral war (but that history is often buried and forgotten)