Who is Captain America?

Steve Rogers is serving in the Army and agrees to take part in an experiment to serve his country. He is given a serum that is supposed to make him a super soldier. The experiment is successful and from now on he fights against the Nazis under the name of Captain America, in the flags of the USA and his iconic shield. Before the end of the war, Steve is frozen in the Arctic and remains in a cold sleep for many years. Many years later he is found and is brought back to life. He joins the Avengers and assumes the role of leader. However, nothing is as usual as Captain America now lives in a world completely alien to him.