The past has always been fruitful ground for storytelling, especially thanks to creators who dig into underexplored niches of history, finding unexpectedly human and complex stories to tell about characters who might not be famous legends. Whether real or fictional, shows like the new Nat Geo series Barkskins are at their strongest when they look beyond the sorts of stories we've heard before — featuring characters we don't often see spotlighted in period dramas. After all, period dramas are haunted by one undeniable trend: Heroes in stories not based on the works of Jane Austen are, more often than …