No matter what you think the ancient Greeks were not on drugs. The people of ancient Greece had an extremely intelligent society. They had sophisticated architecture and a very high level of mathematics in their culture. These areas of life dealt with real things that could be controlled. When it came to natural phenomena the Greeks had certain explanations that might look eccentric now, but were reasonable 3000 years ago. In Greeces history there are several themes that contributed to Greek mythology and reasons it developed. Once Greek mythology was established in the culture an interesting set of gods and beliefs evolved and continued to evolve for hundreds of years. Two of these gods that you are most likely to be familiar with are Zeus and Apollo. If you understand how and why Greek mythology came about, the idea of Greek mythology wont seem so weird.
The location of Greece itself lends itself to many different cultures. It is centrally located between Europe, Asia and Africa. With all three having extremely distinct and varied cultures. Travelers would share their ideas and thoughts with the locals as they went through Greece. Some ideas were adopted into the Greek culture or they were modified to their specific needs. Greece became a melting pot or crossroad for many different cultures. These factors must be taken into consideration when you are trying to understand Greek culture. Another way Greece was influenced by other cultures was by force. Between the years 2000-1400 B.C. Greece was ruled by several different cultures. These outside forces influenced their culture and religion. One thing that remained a constant was their language. The Greeks maintained to keep their native language and this established great internal uniformity. This became a factor in later years helping them rise to such a sophisticated civilization.
The origins of Greek mythology as we know it today are impossible to trace because there was no structured church or written codes, but the main influence is thought to come from the Aegean civilization. The Aegeans lived on the island of Crete and are thought to be one of the first modern civilizations about 3000 B.C. Aegeans believed that all natural objects had spirits. Over time these beliefs developed into a set of legends involving natural objects, animals, and gods with human form. Some of these legends survived as part of classic Greek mythology. The Greek mythographer, Euhemer...