There are heroes, the hugely powerful paragons that fight the 'big bads' and save the world, and there are the people that get roped into the whole chaos that this process entails... This story is obviously about the latter, and how she, as the person who came together with the hero for no bigger reason than sheer luck, was the one who kept the whole kingdom that summoned them alive.
For in times of need, even those that believe themselves to be nothing more than average can rise above what any could hope for.