He was an adventurer, a sharp dresser, an outgoing young man quick to see humor and quick to make friends. He lived in Maine and Florida, climbed mountains in Croatia, skied in the Rockies and loved playing football and watching the Sox and the Patriots.

He accepted his mother’s death from cancer three years ago with faith and courage, and was his father Stephen’s right-hand man through the best of times and the worst.

As roughly 1,000 people filed into St. Maximilian Kolbe Church in Scarborough May 23 to remember 15-year-old Cooper Campbell, they passed photographs that seemed to catch him in motion, a young boy looking up lovingly at his mother, a handsome young man with rakish dark hair and fun in his eyes.

Mourners filled the chapel and an auxiliary hall, and stood back-to-back in the church foyer when there was no more room to sit.

But three weeks after Campbell was killed in a crash allegedly caused by a drunk driver traveling the wrong way on Interstate 95, his death still seemed unreal to those who knew him.

“We’re definitely still in shock,” said 16-year-old Kayla Lauren, a sophomore at Cheverus High School in Portland, where Campbell was a freshman. “I don’t think anyone realizes…”

Raised in Scarborough until he was about 10, Campbell had many friends among the students at Cheverus and Scarborough High School, and students from both schools attended the Mass to bid him goodbye. Other mourners came from as far away as Florida, where Campbell lived for several years.

In his homily, the Rev. Mark Cooper, Campbell’s uncle, urged teens to “not let your hearts be troubled” and have faith in God, reminding them that Campbell packed “quite a lot of life … into too short a time.”

“We have all been stunned and some of us crushed by this tragedy,” Cooper said. “Our hearts have been robbed … of one who radiated a love of life and a love of others.”

Cooper recalled Campbell’s mother, Janet, commenting a few months after her son’s birth that “I never thought it was possible to love anyone so much.”

Later, Campbell became the grandson who was “over the moon in love” will all of his grandparents, yet as a 9-year-old consoled younger cousins at his grandmother’s funeral: “Don’t worry, it’s just like she’s sleeping.”

A few years later, he lost his mother. But he didn’t bury himself in grief, Campbell said.

“After her death, he was strong because he felt her nearby,” he said. “He was close to his dad. They shared the greatest of good times and the saddest of sad times, side by side.”

Like many active teens, Campbell liked adventure, travel and sports. He also liked to “look sharp.”

“He liked clothes,” Connor said. “I wonder where that came from. He was not vain, though I am told he was not opposed to checking himself out in the mirror.”

He also loved brightening people’s days, equally comfortable with small children, older adults and his peers. He made friends easily.

“He gave so much love to the world, and as is the nature of love the world returned it to him,” Cooper said.

The ceremony was attended by Bishop Joseph Gerry, bishop emeritus of Portland, who is Campbell’s great-uncle, along with a dozen Benedictine priests expressing support for the family, said the Rev. John Predmore, the director of mission and identity at Cheverus, which let out classes early and provided buses so students could attend.

Scarborough High School students also mourned their friend. As the young people left the church after the Mass and gathered in a light rain outside, teen girls wiped mascara streaks from each other’s cheeks and boys hugged each other with faces hidden.

“The entire school is here,” said Michael Swords, father of one of Campbell’s Cheverus classmates. “It’s horrible. It touches all of us. It’s so senseless.”

Donna Bartlett, 38, of Wells, the woman accused of driving the wrong way on the turnpike the night of April 28 and crashing into the car carrying Campbell, is currently free on $10,000 bail.

The crash also killed the driver of the limousine Cooper Campbell and his father, Steven, were riding in, James McLaughlin of Gorham. Steven Campbell was seriously injured, but was recently released from the hospital and attended the service.