Most nobles in this time period were former bandits and peasants, because the word "noble" wasn't invented yet.
Well, assuming the chronological paralel with the real world,
nobilitas as a concept comes from the latin tradition, and if we transpose that to the sense of medieval aristocracy, either warrior or palatine, we can argue that the concept existed, especially in the 11th century. Now, nobility and knighthood, as an example for the Vlandian
noble troop line, were concepts that overlapped from the 12th century onward. But knighthood was not - in the wide range of its total expression throughout europe and throughout the period - automatically synonym with aristocracy: you have the knights originary from the
ministeriales in the HRE and the urban knighthoods in the towns of Italy and Iberia, to give a brief example.
Anyway, attributing the designation of
noble line of troops to the elite forces of the Calradic cultures is a concept we must take as creative liberty and I deal with it imagining that these are the recruits coming from families able to pay for better equipment and, thus, from a better social standpoint. These can come from urban or rural backgrounds and so, yes, it causes me no grief to get them from villages.
Replying to OP, yeah, it kinda breaks the immersion for me to turn bandits into knights or other
noble troops, mostly because it would make more sense to see them turn into mercenaries, even of good quality, and this could open the opportunity of expanding these types of troop etc.