In a city where he was supposed to claim the mantle of the Democratic Party for the final time, at a convention where he was supposed to cement his political legacy, President Biden instead passed the torch of leadership, wiping away tears as the crowd rose to its feet in a sustained ovation and chanted, “Thank you, Joe.”

The outpouring of gratitude for his decision to step aside and make way for Vice President Kamala Harris seemed to encourage Mr. Biden as he claimed credit for saving democracy, and for much more, in a nearly hourlong speech filled with optimism and a fighting spirit that capped the first night of the Democratic National Convention in Chicago.

Yet one of the last major moments of Mr. Biden’s political career was pushed well out of prime time on the East Coast after other speakers ran long.

“America, I gave my best to you,” Mr. Biden said. “For 50 years, like many of you, I’ve given my heart and soul to our nation and I’ve been blessed, a million times in return, with the support of the American people.”

Mr. Biden’s speech, and another earlier in the night from Hillary Clinton — who came closer than any other American woman to winning the White House — symbolized how Democrats are moving on from the old guard that has led their party for decades. The convention’s opening night also served to emphasize the historic nature of Ms. Harris’s candidacy, and to frame her as riding on the shoulders of civil rights icons and women who had run for president before her, as she seeks to defeat former President Donald J. Trump.

Here are other highlights from the night:

• A surprise appearance: Ms. Harris unexpectedly took the stage to thank Mr. Biden for his “lifetime of service to our nation.” Her appearance to the pounding rhythm of Beyoncé’s “Freedom” energized the crowd on a night when they had gathered to hear Mr. Biden say goodbye. “Let us fight for the ideals we hold dear, and let us always remember: When we fight, we win,” Ms. Harris told the delegates, who roared back those last five words, which have fast become a rallying cry for Democrats.

• The glass ceiling: Mrs. Clinton told Democrats that the “future is here,” soon after Ms. Harris made her surprise appearance. “I wish my mother and Kamala’s mother could see us,” Mrs. Clinton said in an emotional address that had nearly every delegate on their feet. “They would say: ‘Keep going.’” She added: “This is our time, America. This is when we stand up. This is when we break through!”

• A diverse roster: The opening night’s speakers highlighted the Democrats’ diversity as they celebrated Ms. Harris, the first Black woman and person of South Asian descent to lead a major-party ticket for president. Many were women who spanned the generations and included all races, an unmistakable nod to the glass ceiling Ms. Harris is seeking to break. Representative Alexandria Ocasio-Cortez of New York gave a spirited speech to a crowd that chanted her initials. Mayor Karen Bass of Los Angeles spoke of her decades-long relationship with Ms. Harris.

• A focus on abortion rights: Three women — Amanda Zurawski, Kaitlyn Joshua and Hadley Duvall — shared emotional personal stories about abortion and the post-Roe v. Wade America that Mr. Trump’s appointees to the Supreme Court helped create in 2022. “A second Trump term would rip away even more of our rights,” said Ms. Zurawski, who nearly died in Texas after she was denied an abortion following a miscarriage. They were followed by Gov. Andy Beshear of Kentucky, who won his race in a red state in part by defending abortion rights. “All women should have the freedom to make their own decisions,” Mr. Beshear said, and praised the speakers for their courage.

• And civil rights too: Jaime Harrison, who leads the Democratic National Committee, opened the convention noting that a “Black convention chair and a Black D.N.C. chair lead us in nominating a Black and A.A.P.I. woman to be the next president.” The Rev. Jesse Jackson Sr. was celebrated, appearing briefly onstage. And Senator Raphael Warnock of Georgia spoke of his elderly mother voting for him. “The 82-year-old hands that used to pick somebody else’s cotton and somebody else’s tobacco, picked her youngest son to be United States senator,” Mr. Warnock said.

• Labor’s show of support: Shawn Fain, the president of the powerful United Automobile Workers union, was one of several speakers representing unions that have endorsed Ms. Harris and underscored her commitment to workers. He took the stage in prime time in a red T-shirt that bluntly proclaimed “Trump’s a scab.” In his remarks, Mr. Fain championed a working class at war against the “billionaires class” and “corporate greed.”

• Attacking Trump, early and often: Speaker after speaker condemned Mr. Trump for his actions in and out of office. Gov. Kathy Hochul of New York raised his conviction on 34 felony counts in a Manhattan court. Representative Jasmine Crockett of Texas contrasted Ms. Harris’s career with Mr. Trump’s, saying that “she became a career prosecutor, while he became a career criminal.” Representative Jamie Raskin of Maryland recounted the Jan. 6, 2021, attack on the Capitol, calling Mr. Trump a “sore loser who does not know how to take no for an answer from American voters, American courts or American women.” And Representative Robert Garcia of California said that during the coronavirus pandemic Mr. Trump had “peddled conspiracy theories across the country” while hundreds of thousands of Americans had died.

• From one coach to another: The Golden State Warriors coach Steve Kerr took the stage to praise Ms. Harris fresh from leading the U.S. men’s basketball team to an Olympic gold medal in Paris. “Leadership, real leadership,” Mr. Kerr said, is “not the kind that seeks to divide us, but the kind that recognizes and celebrates our common purpose.” He also praised Ms. Harris’s running mate, Gov. Tim Walz of Minnesota, a one-time high school football coach. “Coach to coach, that guy’s awesome,” Mr. Kerr said.

Jim Rutenberg, Jonathan Weisman and Taylor Robinson contributed reporting from Chicago.