The first night of the DNC did something radical. It let us feel normal again.

You don’t usually need to market normal. But on the first night of the Democratic National Convention, that was the most powerful element of the party’s pitch: Vote for Joe Biden, a regular guy, and you can have some semblance of your everyday life back.

As politics, that’s a modest pitch. But as television, the convention did something impressive: It made ordinary life feel within reach again.

Presidential candidates frequently sell themselves as extraordinary: as Camelot reborn, as a comet from a place called Hope or as an icon of...