Nationalism was a recent invention

I just learned that historians say that nationalism was only invented in around 1800.

I have also read that science was only invented in around 1600, and that before that, it never occurred to anyone to use observation or experiment to guide their thinking.

I have also read that romantic love was also recently invented. Before modern times, couples married for various reasons other than love.

I have heard it claimed that the concept of human races is a modern invention. Until recently, no thought of Caucasians, Negroes, and Orientals as different people.

I have heard that individualism is another modern European invention. Before that, no one thought of people as having indepedent and individual interests. Nobody thought that they could think for themselves.

Until recently, no one understood that gender was a social construct. Well, this claim might actually be true.

And on and on. I don't know what to make of these claims. Most of them seem absurd to me. But I am not a historian.