JFK is not considered one of the best. He didn’t even have a full term, so there’s no way to know. People liked him because he was young and handsome and died that way.
He started the Vietnam War. His only real test was the Cuban Missile Crisis. He did adopt Keynesianism economic policies (over more classical policies) and proposed the bill that became the Civil Rights Act of 1964. Those are all important, but he honestly wasn’t in office long enough to do much.
And besides, like you said he was 43, not 35. AOC would not be able to do anything because she doesn’t have the relationships yet. Good presidents don’t come from the House of Representatives. They come from the Senate (JFK, Obama), Governors (FDR), or Vice Presidents (Harris).