One name used to refer to the First Cause is God. Our reasoning and observational abilities can tell us many facts, some of which we've already noted. For example, the First Cause would have to be immaterial, since matter is always changing. There would have to be incredible power to create so great a universe. The unity and organization of the body, in nature and the universe must also be qualities of the Creator.
Common sense reveals that evil is the absence of good.
Yes, the Creator for some reason allows floods to happen, yet the rain that causes a flood is in itself necessary and often good. Because the Creator is Good and is intellectually superior to Man, we can certainly suppose there may be some good from floods and other disasters we don't fully understand. Most evils are directly caused by people and the choices people make. God could stop us from doing any evil, but to do so would mean that man would be like a robot, a moral slave. We know from experience that sometimes 'evil' moves people to help others, to do good.