Maxperson
Morkus from Orkus
So first, the brothers are fairly highly trained like those in that community are. Second, I acknowledge that there were relatively rare examples of what you are talking about.For example, the show Supernatural.
Neither of the brothers are mages, nor innately magical. But they do on occasion perform magical rituals successfully, because they have seen how magic works and have some familiarity.
In other words, both are proficient in the Arcana skill.
Anyone who participates in a sacred community, akin to a synagogue, church, temple, or household shrine, is performing a divine ritual.
For every example you come up with, though, 10 can be brought up where that isn't the case.