Yes quite obviously we have always had taxes but the "income tax" is less than 100 years old. And yes there are rich and poor in every culture and very definitely their is a structure that fosters a middle class and one which destroys it. Capitalism , AKA freedom virtually created the middle class that we know it today and Marxism always destroys it. Your last sentence is a bit vague, it can be interpreted from either side, if you mean it like Marx did as the "class struggle" then nothing has been so well debunked as the last 100 years with the 130 million deaths Marxism created and the destruction of every economic system it touched.