He is no longer “Uncle Joe.”

Joseph R. Biden Jr., now officially the Democratic Party’s nominee for president, has dabbled in various imagery over the years, including working class champion and regular guy. But the one that has always stuck, and that followed him onto the campaign trail earlier this year, was that endearing and charming but awkward relative, slightly removed; the aviator-wearing cool old dude who you are happy to have around, but with the occasional wince.

Enshrined by The Onion, the satirical magazine, during the Obama administration, and embraced by the Trump campaign, which has exaggerated the caricature into doddering territory, the image may have been put to rest on Thursday night. In a convention finale speech that ranged from the quietly intimate to the soaring, from stories of his lost wife and children to quotes from the poet Seamus Heaney (“when hope and history rhyme”), exhortations and promises to rise to the moment, Mr. Biden saw off the Uncle Joe persona and made a pretty convincing case for another familial role.

Hello, father of the nation.

It was an idea that has been slowly, carefully seeded over the four days of the Democratic National Convention, with its emphasis on family, empathy, the big, all-embracing party tent. And it has been done with words and supporting imagery.

It was done by Mr. Biden’s welcoming, on Wednesday night, of Senator Kamala Harris, his chosen vice president, to “his family.” By his choice to have his children introduce him. By the video of Stephen Curry, the Golden State Warriors basketball player, endorsing him — along with Mr. Curry’s wife and two young daughters, one of whom announced mid-chat that she had to go to the bathroom.

By the extraordinary testimonial from Brayden Harrington, a 13-year-old boy with a stutter, who Mr. Biden took under his wing while campaigning. By all the babies with their parents on the video screens, who served as a sort of stand-in audience to applaud his speech during the remote convention. By the way a group of former rival presidential candidates got together over an online video call to sing his praises, the same way his granddaughters did. By his own words, which promised to protect the country (plus Social Security and Medicare), to love it, to tend to it, to help it become a more perfect union.

By his own presentation. His mane of white hair, swooping back, and now white eyebrows. His well-tailored but not showy single-breasted suit — jacket buttoned to keep it neat — true-blue tie and natty white pocket handkerchief. Mr. Biden has never been one of the fanciest dressers in Washington, but he has always appreciated the way clothes can convey respect for office.

It’s a familiar image, just slightly aspirational — something to grow into. The kind of person you can imagine presiding over family dinners, managing squabbles and reminding everyone to say please and thank you for passing the peas. It makes a virtue of experience, and age. It positions Mr. Biden not as a pushover but as a patriarch. He may be chasing the youth vote — everyone is — but he is not chasing youth.

And it draws yet another line between Mr. Biden and President Trump, who has made a signature out of his love of an extra-long master of the universe red tie; blowzy, oversize suit; fake tan and blond dye job.

Just as the full-body hug Dr. Jill Biden gave her husband after his speech conveyed their deep bond, as did the way they easily held hands as they walked outside with Ms. Harris and her husband, Douglas Emhoff, to wave at the crowds gathered in the fresh air beyond the convention hall and to watch the closing fireworks. It all offered a pointed contrast to the twice-divorced, thrice-married president, whose current wife often seems to be swatting his hand away on camera.

Speaking of which, Mr. Biden also talked about being an “American president” and his belief in “Made in America.” During the convention, Dr. Biden, at least, gave some support to his words, suggesting one of the ways in which she would act as first lady.

Though it wasn’t much publicized, she wore three different American designers at a time when the United States fashion industry has been decimated by the coronavirus pandemic: a green Brandon Maxwell coat dress (on Tuesday, for her speech), a navy silk and lace Ralph Lauren (on Wednesday, for Ms. Harris’s speech) and a draped lavender crepe Christian Siriano (on Thursday, for Mr. Biden’s speech).

Both Mr. Maxwell and Mr. Siriano are known for their embrace of diversity — of age, size and shape — and the belief that everyone has a right to happiness in a great dress. Mr. Lauren’s 50th anniversary show in 2018 was a veritable ode to the extended American family.

The question now is who will be sitting at the head of its table.