The 37-year-old actor discussed the late American astronaut while promoting the movie Wednesday at the Venice Film Festival with director Damien Chazelle and co-star Claire Foy.
First Man follows NASA's efforts to land a man on the Moon in the 1960s. Armstrong, who died at age 82 in August 2012, became the first man to walk on the Moon in July 1969.
Gosling said the film presents Armstrong's success as a "human achievement" rather than a patriotic American victory.
"I think that what Neil achieved was widely regarded as a human achievement, and that's how we chose to view that," the Canadian actor said, according to Variety.
"Neil was extremely humble. He deferred the focus from himself to the 400,000 people who made the mission possible," he explained. "He didn't view himself as an American hero, and we wanted the movie to reflect Neil ... [and] honor the way Neil presented himself."
Gosling said he spent time with Armstrong's family and friends while researching the famously private icon.
"I've never had more help in my life on a film... Whether it was Neil's sons or his late ex-wife Janet or Neil's sister, his childhood friends," the star said, according to Deadline.
"Neil was a very famously introspective, quiet, humble person so the challenge was to honor that but also to create windows into what he might be or had been experiencing emotionally at the time," he added.
Universal Pictures released a new trailer for First Man on Wednesday. The movie is based on the James R. Hansen book First Man: The Life of Neil A. Armstrong, and opens in theaters Oct. 12.