We are often most unhappy with what is most human about us. This is the basic form of oppression that class society imposes on us. This is not to say that everybody is happy with their sex lives, body shape or overdemanding kids. Class societies, including capitalism, were historically justified in that they raised the general level of material output and technological progress even at the cost of great social conflicts and general alienation. Now this is no longer true.
Class society holds back further development and alienation is unnecessary.
Alienation will only be eradicated when the division of labour takes place freely and in a society where labour is not bought and sold, and not compulsory. That is why only communism can liberate humanity. Under communism labour is freed. Workers are the masters of the process of work and the products of their labour. In collective, voluntary organisations they will choose what priorities they want for dividing up the social product.