Human life on Saturn is impossible because Saturn is a gas giant without a solid surface on which to support life. The extreme pressures of Saturn's atmosphere also make it a particularly inhospitable place.
Saturn is composed primarily of hydrogen and helium, the same elements that make up the sun. When descending inwards toward the center of Saturn, one would first encounter a gaseous layer. Next would be a layer of liquid hydrogen. Assuming the craft travelling to Saturn could survive the extreme pressure, eventually it would reach a small, hot, rocky core surrounded by solid metallic hydrogen. Temperatures in the core can reach 21,000 degrees.