Were there any real-world analogues to the way the Starks invite some of the smallfolk into their feasts and care for them during the winter, or Margaery Tyrell’s “Woman of the People” characteristics, or are those kinds of things made up by GRRM to give us a more modern way of signifying who the less “evil” nobles are?

Yes there is. Given the emphasis on charity to the poor in traditional Christian teachings, nobility and royalty made a big show of helping the unfortunate – everything from giving leftovers and handmedowns to beggars at the gate to giving money to the church for hospitals and orphanages to giving alms on Maundy Thursday, to washing the feet of the poor in imitation of Christ. 

These kind of gestures were a core part of the medieval social contract – the quid pro quo for deference and obedience was at least a symbolic expression of noblesse oblige.