No one, besides yourself, is arguing that what you said is grammatically correct. However, read the two articles, count the number of comedians, then read your summary. Claiming you didn't misread the text by making excuses for your misreadings, "The author's name or gender convey no useful information." isn't a good defense.
Remember when you thought 1 = 2?
Slave patrols, overseers and managers, were all mentioned in the article. Also the sole focus of any army was combat. However, their reason for combat i.e. slavery can differ.
Italians and Irish were both indentured servants, not slaves. Nor were they slaves in 1850, the period which we're talking about. Also Rome was conquered in 1850 and had no government. Ancient Rome stopped being a thing many centuries earlier.
Ok, but I'm not talking specifically about groups and more about Chiefdoms, as the social structure in the 1700's-1800's was more structured than the earlier "groups". Especially since many "groups" (Protestants, Catholics, French, and English) composed the US. But, one of Diamond's characteristics is the fluidity between the micro and macro level examples. So let's use your group example.
White people in America were formed around a grain crop (Tobacco, Wheat, Cotton) with a trainable animal (Black people). The previous groups lost their traditional clan identifications (language, nationality, religion) and adopted a new one (race).
I could also never put my face on a bench, so I guess different people have different goals?