Well there are few archetypes for the "lucky person". There are many example to choose from. X-Men's Longshot and Domino, Good Luck Girl's Ichiko, Disney's Gladestone Gander, Dresdenverse's Michael Carpenter and Father Forthill, LOTR's hobbits.
The Born Lucky
This person is born lucky. Fortune smiles on them for some reason. A dozen orcs trow javelins at them and only one hits. They just happen to step on the giant's foot when dodging his club. They draw the only hand that could win in the poker game the first time they play. They choose the red wire because their mom's hair is red and the bomb doesn't explode. Not everything goes their way. They fail. But when everything depends on one thing happening, you want them to do that.
The Blessed by the Unseen
These people are blessed by a higher power because of something they do. Someone up there or down below is personally helping them succeed and they believe it. It is their motives that keep divinity on their side. These can come off as the old school cavalier or paladin who doesn't have outright magic powers but seems to resist harmful effects and take down stronger foes.
The Good Luck Charms guy
These people believe all the superstitions and follow them religiously or by indoctrinated compulsion. But unlike our world (maybe), these charms and rituals to ward off bad luck works.
The key aspect is that the base character is just skilled enough in something that people entrust him or her in their party or for important roles. It's their good luck that removes second guesses. The lucky person might one shot the enemy wizard but that is just 1 of 20 monster fought that day. He or she still can go toe to toe with orcs, but not at the level of a fighter or rogue who has reliable skill.
The Born Lucky
This person is born lucky. Fortune smiles on them for some reason. A dozen orcs trow javelins at them and only one hits. They just happen to step on the giant's foot when dodging his club. They draw the only hand that could win in the poker game the first time they play. They choose the red wire because their mom's hair is red and the bomb doesn't explode. Not everything goes their way. They fail. But when everything depends on one thing happening, you want them to do that.
The Blessed by the Unseen
These people are blessed by a higher power because of something they do. Someone up there or down below is personally helping them succeed and they believe it. It is their motives that keep divinity on their side. These can come off as the old school cavalier or paladin who doesn't have outright magic powers but seems to resist harmful effects and take down stronger foes.
The Good Luck Charms guy
These people believe all the superstitions and follow them religiously or by indoctrinated compulsion. But unlike our world (maybe), these charms and rituals to ward off bad luck works.
The key aspect is that the base character is just skilled enough in something that people entrust him or her in their party or for important roles. It's their good luck that removes second guesses. The lucky person might one shot the enemy wizard but that is just 1 of 20 monster fought that day. He or she still can go toe to toe with orcs, but not at the level of a fighter or rogue who has reliable skill.