Of course ressentiment is constant, but the question is which kind of thinking dominates society?
Historically, the pendulum has swung back and forth between what Nietsche labeled master and slave morality. The Roman empire is a typical example of master culture: it's good to be rich and powerful, and it is right for the strong to dominate the weak. There might have been ressentiment among the Barbarians the Romans conquered, but the dominant culture certainly didn't sympathize with them.
Then in Europe we get the rise of Christianity, a typical example of slave morality which regards strength and power as evil (the New Testament is full of messages like the meek will inherit the earth, it's easier for a camel to pass through a needle's eye than for a rich man to enter heaven, etc.)
Then Western civilization swings back to Master morality: the crusades as an early example, later manifest destiny, the white man's burden, the rise of fascism in Europe, etc. Then after WW2 fascism loses its luster and the pendulum swings back.
Western colonies which were previously considered mutually beneficial developments are now condemned as exploitative of the less advanced native cultures. People like Columbus who were once lionized for their discoveries and conquests are now condemned as villains.
You can view the American civil war as a midpoint of the pendulum's swing: while Negroes, who are poor and uneducated, are not (yet) considered morally superior to Whites, it is no longer morally acceptable to enslave them just because you can.
Today, the pendulum has swung fully towards slave morality. You should check your privilege, and shut up, so the oppressed may speak. Representation is important. The rich and powerful are almost by definition evil. Bill Gates and Elon Musk won't be remembered in the same way as Rockefeller or Ford. Racism is no longer racism, as it was in Martin Luther King's time, but now it's prejudice PLUS power (also everyone has racial bias, so by the very definition, the powerful are evil, while the powerless are innocent).
So while you can argue that the pendulum has swung back and forth on this topic through history, and it's hard to say if slave morality is currently at an “all-time high”, I think it's undeniably true that we are currently heavily biased towards celebrating the powerless over the rich and powerful.