The central conflict in "The Lottery" is Individual vs. Society, showing the individual's struggle against collectively accepted norms. Tessie Hutchinson refuses to accept that her family, and then she herself, has been chosen for the Lottery, but her protests are ignored and overpowered by the collective assurance of the ritual's acceptance.
Tessie Hutchinson was in the center of a cleared space by now, and she held her hands out desperately as the villagers moved in on her. "It isn't fair," she said. A stone hit her on the side of the head.
Old Man Warner was saying, "Come on, come on, everyone."
(Jackson, "The Lottery," classicshorts.com)
Old Man Warner represents Society, the purpose which is condoned by the village as normal and even virtuous. Tessie represents Man, the individual who fights against norms but, in this case, is destroyed by them. Her fight comes from a selfish, personal desire for her family to be spared by the Lottery; since the society of the village expects every member to be equally invested in the outcome, her rebellion is quickly put down. The outcome of the story shows that Society, in this case, is victorious, and there is no sign that the Individual has had much effect on other opinions.
A story must be dramatic in order to be interesting. It must contain conflict in order to be dramatic. "The Lottery" is certainly interesting, so it must be dramatic and must contain conflict--but it is very hard to see how there is any conflict between any of the characters or any institutions. For instance, there is no interaction between Old Man Warner and Tessie Hutchinson. They don't even talk to each other. When Warner does talk he does not sound like a protagonist but like a parrot mindlessly repeating what he heard others saying long ago.
I suggest that the main conflict in the story is between abstract principles and not between characters. The conflict might be described as past versus present, tradition versus enlightenment, superstition versus reason, or ignorance versus truth. The protagonist in this conflict would be the past, or tradition, or superstition, or ignorance. The antagonist would be the simple truth, including the truth that human sacrifice doesn't make the corn grow.
The people in the story are present because it is obligatory. The man in charge of the drawing is anxious to get it over with so that everyone can return to the normal business of living. Something is forcing all of them to participate in this deadly lottery even though each privately dreads being chosen and probably dreads the guilt he or she will have to live with for a long time after the stoning. The antagonist would be the slow progress of understanding which is destined to win in the end. Two of the characters remark that lotteries such as this are being given up in neighboring communities. They are the voices of reason. When the Hutchinson family is chosen, a girl in the crowd is heard to whisper, "I hope it isn't Nancy." Hers is the voice of human compassion. And finally when Tessie gets the fatal black spot, she voices the plain and obvious truth.
"It isn't fair, it isn't right," Mrs. Hutchinson screamed, and then they were upon her.
For the time being, the protagonist--superstition, tradition, ignorance--is still in command.
Central conflict describes the main conflict in any story. Central conflict usually comes in several forms. However, the form displayed in “The Lottery” is Man versus Society. In a Man versus Society conflict, the main character is not in sync with the other characters in the story. Tess, the main character in this story, made it obvious that she was different from the other women in the village. Tess was the only woman not present at the village gathering. In fact, she arrived late and shortly before the lottery began. Also, it was obvious the other people in the village saw the lottery as one of the most important events of the year. However, Tess was home cleaning and did not know where her husband or children were. Tess’ behavior before, during, and after the lottery drawing evidences her inability to adjust to the norms of the society in which she lived.