Whats is humanism and how was it reflected in the arts of the early renaissance?
Humanism is the school of thought that focuses more on human philosophies, values and concerns rather than focusing on the divine. Humanism came to the forefront just before the start of the Renaissance, so many of the artists at the time were keen to express this form of thought in their works. Therefore, it is common to see paintings that are more people-centric rather than paintings devoted to saints, deities, and other religious references.
A book that might be very helpful to you in this vein is A World Lit Only by Fire: The Medieval Mind and the Renaissance: Portrait of an Age by William Manchester.