Eloise Smith, 23, posted a reaction video on TikTok immediately after listening to “Now and Then,” the Beatles song released on Thursday.

“Can’t believe it’s 2023 and I get the joy of hearing a new Beatles song for the first time ever,” she wrote in the video’s caption.

In an interview, Ms. Smith, a civil servant who lives in Manchester, England, said she was a third-generation fan: Her grandmother introduced her father to the Beatles, and her father introduced them to her.

“I was 1 when George Harrison died,” she said.

Ms. Smith, who has a forearm tattoo of the band’s “Abbey Road” album cover, said she was “thrilled” weeks ago when she heard about “Now and Then.” The ability to immediately react and connect with other fans of the band through social media has made the experience of hearing a new Beatles song richer, she added.

“Rather than just being in the kind of bubble of your friends, you can speak to people all over the world about it,” she said.

The Beatles came late to digital media. The group did not sell downloads of its songs at Apple’s iTunes store until 2010, seven years after it had opened for business. When streaming became the main medium for music fans, the Beatles held out once more, waiting until 2015 before making the band’s work available on Spotify, Apple Music and other platforms.

The decision to go digital allowed new generations of listeners to more easily discover a group that had won the adoration of mobs of screaming fans in the 1960s. Now, Gen Z listeners regularly post Beatles-related videos on social media platforms.

“This song is my Roman Empire,” one listener wrote in a TikTok post, referring to a meme claiming that men think about the Roman Empire at least once a day. In comments, several people replied that the video was making them teary. “Sobbing,” they wrote. Others said they were excited to listen to the song with their grandparents.

Skylar Moody, 24, said she spent most of Thursday trying to avoid “Now and Then” spoilers. A superfan whose social media presence is almost entirely devoted to all things Beatles, she wanted to record her reaction to her first listen, which meant waiting until she was finished with work. She kept her phone on silent all day, lest she accidentally hear a snippet of “Now and Then” while scrolling online.

Ms. Moody, who lives in New Jersey and goes, fittingly, by @lucyinthesky.lar on TikTok, said she became a Beatles fan after watching “A Hard Day’s Night,” the group’s 1964 film, during a music history class in high school. She described the Beatles’ online fandom as “very diverse and also unified.”

“No matter what age or demographic you’re in,” she said, “we can all come together in one agreement that we love the Beatles.”

She continued: “This is where we find our people now. It’s so easy to go on social media and find a fan community of people to talk to that will understand you.”

Late on Thursday afternoon, she made a reaction video of herself listening to “Now and Then” in her car. “I’m listening to the Beatles! In 2023!” she exclaimed, clutching her face through a two-minute clip in which she describes what she’s hearing.

The Beatles’ company, Apple Corps, has billed “Now and Then” as the group’s “last song.” It’s the third one since John Lennon’s death in 1980, after “Free as a Bird” and “Real Love” in the mid-1990s. All three were built on home demo recordings made by Mr. Lennon.

“My heart feels so heavy right now, but in a good way,” Ms. Moody said in another TikTok video, adding, “We are experiencing their last song together, and this is going to go down in history. I’m so happy that we get to share it all together and that we’re able to share our thoughts like this online with people who get it.”

Ms. Smith, the civil servant in England, said that she would try not to wear out “Now and Then” in the coming days. “I’ve been kind of listening to it every once in a while, to savor it,” she said, “because it’s such a big deal.”