How did the overproduction of food lead society out of the Dark Ages to the Renaissance?

In the second part of the fourteenth century, European society was beset by wars as well as social conflicts and political fragmentation combined with an institutional crisis in the Catholic Church (the Great Schism). During the Great Plague (1347–1349), one third of the European population died. Subsequent epidemics maintained a high level of mortality. Many survivors became relatively wealthy when they inherited the property of the deceased. Labor became scarce and wages rose, stimulating the interest in creating new, labor-saving devices.
At the same time, individualism grew as people sought to turn away from their disintegrating society, which was undermining their sense of common purpose. Some turned to mysticism (e.g. Geert Groote, founder of the Brethren of the Common Life, and Thomas à Kempis in the Netherlands), while others moved to a new, more secular worldview seeking refinement, abundance of good things, and self-expression in this life, which was painfully short; an example of this is Bocaccio’s Decameron, which influenced Chaucer’s Canterbury Tales.
Food prices dropped and, apart from episodes of war-related scarcity, there was relative abundance of food while the prices of manufactured goods increased, sometimes dramatically. There was a growing demand for meats and spices; this stimulated the development of the spice trade. Venice defeated Genoa and gained monopoly control over the supply of spices from Egypt; as a result, in the fifteenth century, spices became incredibly expensive. This, in turn, led to the search for alternative supply routes and the expansion of European geographic horizons. This quest, together with the search for the sources of African gold, brought Europe into the Age of Discovery.
At the same time, the wool and silk industries were developing rapidly, and greater financial sophistication was emerging, especially in Renaissance Italy, where Genoa’s Banco di San Giorgio became the first public bank. At the same time, Italian cities developed the mechanism of public debt and began issuing bonds to finance their military and commercial expansion. This financialization of the economy combined with the growth of international trade to enrich the European (especially Italian) middle class, which sought to assert itself against the nobility and enhance its own status by popularizing new cultural practices.
In the fifteenth century, the Medici, an influential banking family, became the rulers of Florence; they, and other Renaissance rulers, created a new court culture emphasizing the arts. New humanist educators criticized Scholastic philosophy with its abstract logical frameworks and instead stressed the study of Greek and Latin literature and the central importance of this worldly self-realization and individual brilliance regardless of social origins.