MGibster
Legend
I don't understand why you think that? You object to a farm boy being a fighter because they haven't got training, but you also object to the farm boy being a fighter because they have special powers because they are the son of a god/Darth Vader/the rightful king/the Chosen One which stands instead of training?
In 5E terms that character is likely a Fighter with the Folk Hero background. Her or she may have started out as a humble farmer, but by the time we see them at 1st level they are a well trained Fighter. Maybe it wasn't formal training like the Knight received, rather it was informal on-the-job training. The use of backgrounds in D&D 5E indicates that even 1st level characters have some sort of past. They didn't just wake up this morning and find themselves 1st level adventurers.