Will the Kennedy assassination ever lose its cultural centrality? Even as organic memory of the event fades, new works of pop art like Jackie (2017) and 11.22.63 (2016) attest to the powerful ongoing significance of the event. The slain president turned out to have much more weight dead than living.

Woodrow Wilson once claimed that while men die, ideas live. John F. Kennedy had no ideas but in death he became one. All the zesty confidence and breezy chutzpah of the American century became flesh in JFK, though like him it would never recover from what happened in Dallas. The United States now had a wound that was worthy of Shakespeare, what Don DeLillo memorably called the moment ‘that broke the back of the American century.’

The assassination, with its catalogue of secrets, its endless theories and rituals, its theology of patterns and links, has become a true dead end. The central player in the drama – Lee Harvey Oswald – is a slapstick figure straight out of a Marx brothers movie. Oswald bumbled into history like a child causing chaos in a gift shop. The riddle of his life is how he made a fool out of the greatest power the world had ever seen.

The Kennedy mantle passed to Bobby, who was himself gunned down in 1968. The third brother Ted was the next to have a crack at the big prize in 1980. Asked why he wanted to be president by CBS News’s Roger Mudd, Teddy, agonizingly, had no real answer. Perhaps he wanted to be president because being president was something that happened to people like him. Such is the attitude of the Kennedys, to whom power is an inheritance, an heirloom, a reflex.

He wasn’t the only one to be upended by the Kennedy banana skin. The JFK mythos has mesmerized the Democratic party ever since. Bill Clinton surely had the self-image of a Kennedy-style womanizer, even though he was seducing chubby interns rather than Hollywood starlets. Barack Obama was undoubtedly the coolest president since Kennedy. Both blended youthful vitality, sharp tailoring and a strutting, know-it-all confidence into an ultra-creditable package for the mass media. Kennedy and Obama made their supporters feel good about themselves (to the point of smugness) and both believed that gorgeous rhetoric was a better tool with which to shape an era than the gritty matter of actually legislating.

Like Kennedy in Cuba and Vietnam, Obama blundered in Syria. Away from the undoubted style and eloquence, there is the same terrible legacy: the abuse, misuse and non-use of American power, with stacks of corpses to show for these errors. Not that many people can look past the eloquence or the style. As Jack put it to Gore Vidal after the Bay of Pigs fiasco: ‘In this job, the worse you fuck up, the higher the ratings.’

The legacy of Kennedy, slavishly followed by the Clintons and Obama, is a belief that if you have enough intelligent people in the room you can solve almost any problem. This is a suave, patrician kind of politics. Gather together the most impressive fellows, all self-assurance and valuable connections – fellows who know how things ‘really work’ – who are happy to conduct business in between conversations about their Harvard days, and let them sort it all out. History is just something unpleasant that happens to other people.

Eventually these administrations make half the country feel stupid. As such Richard Nixon and Donald Trump, in their 1968 and 2016 guises as fiery tribunes of middle-American thickos, were natural democratic reactions to the ironic self-regard of the Kennedy brothers and Barack Obama.

JFK’s brutal murder was a terrible moment for America and, perversely, the best thing that could have happened to the Kennedy family. The Camelot that paid the tragic levy of blood (twice) in the service of the Republic is a powerful legend that no committee room PR operation can ever hope to match.

All Democrats are measured against this myth of confidence and promise, with Beto O’Rourke the latest to fall short of it. For all Clinton and Obama’s mimicry they were never quite adequate as successors to Kennedy either. Bill was too gangly, too southern, too eager to please; Barack was too serious, too cerebral, too pompous.

Impressionists are never as good as the real thing. The future of the Democratic party at the national level isn’t Beto or Kamala Harris. It’s Jack Kennedy Schlossberg, JFK’s grandson. With the scintillatingly crisp hair and angular profile of a man who was born to be photographed, Schlossberg looks as if he were designed, engineered and conditioned for optimum media salivation.

As his grandfather once showed, there isn’t much more to the presidency than that.