The first quest of Stardew Valley is called introductions and the goal is simply to meet all 28 non-player characters that live around Pelican town at the beginning of the game.
You start at 2 / 28, having already met mayor Lewis and Robin during the intro and when you meet a character, the number goes up. The Wizard does not count, as his tower is locked for a few days at the beginning of the game.
You might get stuck at 27 / 28 as I did. What the game doesn’t tell you is that you need to say hello to the characters outside of work. In my case, the missing character was Willy, who spends most of his time selling fishing rods and lures at his counter.
As seen in the picture above, the trick was to simply go around the counter to talk to him in private, and then the quest was completed. It’s probably the same thing for Pierre and Clint.
List of the remaining characters