“Triangle and Sadness” and “Babygirl” star Harris Dickinson has delighted the Cannes crowd with his feature directorial debut “Urchin.”

The film, led by “Fear the Walking Dead” star Frank Dillane and a vivid portrayal of homelessness and mental health on the streets of London, had its world premiere in the Un Certain Regard competition. “Urchin” earned its new filmmaker and his cast an enthusiastic 5-minute ovation.

Dickinson looked relieved at the reception, waving across the room to whoops from the crowd.

“It’s really an honor to be here and to share it with you guy is special,” he told the audience before the screening. “I’m nervous. I hope you enjoy it and if you don’t, tell us gently.”

Judging by the response, few didn’t enjoy it. Among those joining in the ovation was Paul Mescal, soon set to star alongside Dickinson in the upcoming quartet of...