The Renaissance started in Italy because there were small breaks in the Christendom atmosphere and environment that had previously shaped Italy, which led to a freedom and independence. This newfound freedom and independence along with the presence of the ruins of Roman civilization led to the Renaissance.
The Renaissance began first in the Italian city-states. These city-states had wealth from commerce and trade that were present in the Middle Ages. Venice was known for its transportation in the silk trade and the spice trade. Many merchants from India and China came in helping to bring along new ideas.
The Renaissance was able to grow continuously, thanks largely in part to the wealthy bankers in this area. These bankers patronized the arts by employing famous painters, architects and sculptors. Italy also developed an appreciation for the classical age and was able to truly live in that appreciation as Italy had many remnants from the classical age through the Romans. There was the Roman's road network, their public buildings, their monuments and their aqueducts system to be admired and researched.
Italy is also thought to have been a country that could stimulate the individualism and creativity seen in the Italian Renaissance due to its small size. It was a much smaller city-state compared to those countries surrounding it.