What a year.

When the clock struck 12 last Dec. 31, a sense of hope filled the world as COVID-19 vaccines were on the horizon and a return to normalcy felt within reach. Life had other plans, as it turns out, but there was still a lot to celebrate in 2021: baby steps toward a post-pandemic life, reunions with loved ones ... an actual reunion of Friends.

This year has been a transformative one, pushing us all to create something new and hopefully better for our lives. This issue reflects that spirt: Our People of the Year cover stars have all led the way in their fields to help make the world a little bit better.

Dolly Parton has always done her part to help others through efforts like her Imagination Library, which to date has given more than 160 million books to kids in need. Early in the pandemic she saw another way to help, donating $1 million to Vanderbilt University Medical Center to support COVID-19 research, which resulted in the Moderna vaccine that became widely available this year.

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"It makes my heart feel good to know that I can do something for somebody else," she says.

At a time when levels of Anti-Asian hate crimes rose significantly, Sandra Oh stepped up and used her celebrity for good, speaking out after the spa murders in Georgia. And she continued to work on transformative stories, signing on as producer on her Netflix series The Chair and other new projects that showcase perspectives and voices she believes in.

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"Progress is not just sticking a bunch of people of color [into a show] and having them speak like everyone else," she says."The thing that I'm most proud about with The Chair is how it's translated to people of color who are living and working in mostly white spaces. What I hope is that anyone who's watching it can say, 'That could easily be me.' "

Simone Biles, meanwhile, redefined what it means to win in sports. At this year's Olympics, she stood up for herself and changed the way we think about athletes' mental health. "Now [people] view me as human, which makes me so happy," she says. "I fought hard. I survived. I'm proud of myself."

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And then there are our nation's teachers, whose resilience has been unbelievably inspiring these past two years. Juliana Urtubey, National Teacher of the Year, was chosen along with finalists John Arthur, Alejandro Diasgranados and Maureen Stover to represent the 3 million-plus classroom heroes who have gone above and beyond to ensure our nation's kids have bright opportunities ahead. Our future depends on supporting them and their work.

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And it depends on looking forward with hope once again. As Oh tells PEOPLE, "When you understand what you've gone through … you remember that you've lived."

Read more from our People of the Year in the latest issue of PEOPLE, on newsstands Friday.