I got a philosophical question for you. And I'm going to have to be careful of my phrasing as not to sound racist.
So, there is a racial hierarchy to the world. If there is a spider in my presence that I want to get rid of, I could squish it and generally ppl won't mind. I personally know some ppl who would not like me squishing a living thing but I won't get charged with anything. If there is an animal like a stray cat I want to get rid of, killing it will earn me a lot of disapproval. Maybe even an animal cruelty charge. But I won't get charged with murder. If there is a person who i want go get rid of, I would have to leave the premise. Killing the person will get me a murder charge.
So, racial hierarchy right there with bugs near the bottom then animals, then other humans. And while racists will argue that their race is somehow better, I think we here can all agree that a difference in melanin, the presence or lack of ridges on your skull, or the presence of a snake in your head doesn't make you superior. It's a common thing in scifi to have an alien race trouncing around the galaxy because they think they're better than everyone else when in reality they're not. If an Ancient, an Ori, or Q decides to say 'he who hesitates disintegrates' then decides to Thanos snap someone out of existence, we would say they're not superior and they need to face some form of punishment for murder because super powers don't make you superior.
So what does? What does an an alien race have to be/possess in order to be undeniably superior to the point that they have a right to view humans as bugs? Is the hierarchy a sliding scale? Whatever we have over the common cockroach the aliens need to have something equivalently superior that humans don't have? Or is the hierarchy more of a line? Those who are above this point are not allowed to stomp on each other.