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.