fresco
The harpsichord was a popular instrument during the Renaissance.
The lute was a popular instrument during the Renaissance.
Triangular composition was most popular during the Renaissance.
Plain song was not a popular form during the Renaissance period.
Gregorian chants were not a popular form during the Renaissance period.
The most popular playwright associated with the renaissance is of course William Shakespeare. It was not always so, and a lot depends on how you define the renaissance.
Jazz was the most popular type of music during the Harlem Renaissance.
The renaissance painters in Florence considered the drawing (contours) to be the true essence of a painting. The Venetian contemporaries, as Giorgione, Titian and Tintoretto, were of the opinion that colour is the heart and soul of a painting. So that is what they developed.
They were important because there were NO cameras back then. Could you imagine not having one single picture of you in your entire house?! :\ Unfortunately, mostly only wealthy people could afford portraits made for themselves.
lute
Some form of oil painting was used for the first time to create Buddhist paintings in India and China, but the technique didn't really become popular until after the 15th Century, even becoming the most popular painting technique during the later Middle Ages and the Renaissance.