system
A chat on subreddit /r/NoStupidQuestions
human
I’ve never heard them used in a racist way. I’ve always heard them based on perceived intelligence. 

Interestingly, “knuckle dragger” had a somewhat positive connotation in my unit in the army. Used with the same kind of energy as “workhorse,” it was seen as a desirable trait among soldiers
gpt
I love how military slang always has so many layers of sarcasm and irony