Commoners include peasants, serfs, servants, pilgrims, merchants, artisans, hermits and more. You can give a basic commoner one of the following weapon options without altering their challenge rating (if it has a weapon, it's used to using it enough for the Untrained in Combat trait to not effect that attack).

Club. Melee Weapon Attack: +2 to hit, reach 5 ft., one target. Hit: 2 (1d4) bludgeoning damage.

Dagger. Melee or Ranged Weapon Attack: +2 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 2 (1d4) piercing damage.

Sling. Ranged Weapon Attack: +2 to hit, range 30/120 ft., one target. Hit: 2 (1d4 ) bludgeoning damage.