At The Fabelmans premiere Sunday at AFI Fest in Hollywood, California, Williams told PEOPLE that playing the character Mitzi Fabelman — loosely based on Spielberg's own mother, Leah, was "a great place to live" as an actor.
"Myself, I'm a little quieter, I'm a lot shyer," the 42-year-old actress said. "And so, to live as this person for this period of time was really... I learned a lot, and I hope I take a little bit of that love of life with me."
Williams emphasized that her and the cast of the movie — which also includes Gabriel LaBelle, Paul Dano, Seth Rogen, Judd Hirsch, Jeannie Berlin, Robin Bartlett and Julia Butters — "love each other a lot" after making such a personal film with 75-year-old Spielberg.
"Every time that we're sort of brought back together and we get to see each other again, it's like coming home," she told PEOPLE.
"I think seeing how connected [Spielberg] is to his childhood is really inspiring, that that's a place that he continues to draw from," Williams added about working with Spielberg.
In May, Williams told Variety about being asked to play a character based on Spielberg's late mom in the semi-autobiographical project.
"We were sitting around the house in COVID, with one day looking a lot like the next, and my phone beeped and I had a message that Steven wanted to talk to me," she said. "I couldn't comprehend that he might want to work with me. I thought he had a question or something. Then he got on the Zoom and told me that he wanted me to play this person, his mama."
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She added of the movie, "It's funny, it's sad, it's kind of everything. It's the muchness of life. We're trying to reflect all of that."
Last Wednesday, Spielberg told The Hollywood Reporter that his parents had been "nagging" him to put them on the big screen prior to their deaths.
"They were actually nagging me, 'When are you going to tell that story about our family, Steve?' And so this was something they were very enthusiastic about," he said.
He also shared what finally prompted him to make The Fabelmans: "I started seriously thinking, if I had to make one movie I haven't made yet, something that I really want to do on a very personally atomic level, what would that be? And there was only one story I really wanted to tell."
Ron Galella, Ltd./Ron Galella Collection via Getty Steven Spielberg (far right) with his parents in 1989
Spielberg's mom Leah died in 2017 at 97 and his dad Arnold died in 2020 at 103.
Spielberg — known for classics like E.T., Jaws, Indiana Jones, Jurassic Park, Schindler's List and many more — said The Fabelmans is "the first coming-of-age story I've ever told."
"My life with my mom and dad taught me a lesson, which I hope this film in a small way imparts," he told THR. "Which is, when does a young person in a family start to see his parents as human beings? In my case, because of what happened between the ages of 7 and 18, I started to appreciate my mom and dad not as parents but as real people."
The Fabelmans is in select theaters Nov. 11. It opens nationwide this Thanksgiving.