There’s multiple components to what “happiness” entails. One might argue that a society filled with numerous cultures and ethnicities all vying for their own interests can make for quite a bit of unhappiness. E.g., if everyone was white, there’d be no hand-wringing over white supremacy. If everyone was straight, there’d be no hand-wringing over LGBT representation, and so on. That’s not saying that other social ills can’t exist in homogenous societies, but they do have fewer due to having more shared identity and values. Don’t be dense just to make a point.
> You're reducing all the diverse peoples that made up the nation into a single group based on their skin color.
Like people do today when lumping everyone of various ethnicities into the “white” bucket and decrying “whiteness”? If it’s a valid classification today why can’t we use the same term retrospectively?