TL;DR
"From about 1330 to 1530, the city-states of the Italian peninsula emerged as the intellectual and artistic centers of Europe. It was a period during which classical texts were rediscovered, thereby reviving the ideas, architecture, arts, and values of the ancient Greece and Rome. By celebrating the beauty of nature and the dignity of mankind, Renaissance artists and scholars helped shape the intellectual and cultural history of the modern world. [...] [many] Renaissance sculptors and painters, enjoyed the patronage of wealthy familied and produced some of the immortal works of the European experience."
The prized possession of the Renaissance? Its artists
"'In Italy, one does not care for the renown of great princes: it's painted only that they call divine.' [...] during the Renaissance the status of the artist rose."
Neo-platonic influences
"Renaissance artists reflected the influence of the Neo-Platonists. In the late fifteenth and early sixteenth centuries, the Neo-Platonists appropriated Plato's belief that eternal ideas - such as beauty, truth, and goodness - existed beyond the realm the everyday life. Humanists belived that the mind could transcend human nature and come to understand these eternal ideas. The artist could reproduce the beauty of the soul through the imagination and in doing so could reach out to God. To Dante, art was 'the grandchild of God.' For Michelangelo, beauty 'lifts to heaven hearts that truly know'."
"Reflecting Neo-Platonist influence, Titian early in the sixteenth century strove to bring the viewer of his paintings closer to the idea of the eternal form of female beauty that he sought to represent with his depictions of Venus."
Depictions of artists
One of the ways that artists went against the scholastic tradition was by painting ordinary people, which was controversial because paintings were seen by the clergy as reserved only for transcendental beings.
"'It is the disgrace of our age that it tolerates the portraits even of tailors and butchers.'The growing popularity of secular subjects may have reflected a reaction against the power and venality of the clergy."
Fundamental political unit
The city-states were the "fundamental political unit of the Italian peninsula" and the backbone of the Renaissance. They offered political leaders the right density of talent of various parties required to make the Renaissance possible (from artists to patrons).
Popolo grasso
With the rise of the "new money" (also known as popolo grasso, or "fat people"), nobility titles started to fade into the background in the Italian peninsula as status became closely aligned with commercial success. The "new money" began to slowly dominate the political landscape as the inversion of status took place.
There are a few reasons why Florence became the main center of the Renaissance. First, many public officials were trained in Roman law and Latin. Second, the Medici were able to infuse a predominantly Christian tradition with many secular elements from the ancient tradition. Third, Florence engaged in extensive trade that focused on luxury products which created the "taste" of the ruling elites (often found in commerce and banking), which made them more receptive to "artistic innovation" than any other place. Fourth, the education system in Florence was one of the best in Europe during that period.
"[Florence] had many schools, including a university, and boasted a rate of literacy probably unmatched in Europe."