95%+ of laborers in the MA were farm workers. No uniting allowed for them.
The guilds in the cities were sort of a cross between labor unions and monopolistic organizations of businessmen. With the latter aspect growing in importance all the time.
The common man did not have it very good during the Middle Ages, although admittedly better than most during antiquity, especially late antiquity.
The Middle Ages saw the establishment of free cities with free citizens. That is one of its great accomplishments. It also saw the establishment of Republics. It was the wealthy merchants of these Medieval Republics that supported many of the artists and scholars of the Renaissance.
The original article of this thread mentions the Cathedral of Florence. Most of that church was build in the Middle Ages. That is very evident in the style of the bell tower at the front of the church. As for Brunelleschi's dome, that was paid for by the Wool Guild of Florence. How do you get the dome without those institutions that were created in the Middle Ages? Even his dome used a Gothic ribbed construction in the outer shell as well as a pointed arch.
As for the peasants working the land, did the Renaissance set them free? I think the French Revolution some centuries later answers that question.
Of course all the accomplishments of the Middle Ages must be debunked by the modern who expects every age to be a mirror of some perfection that has never exited and never will exist.