Final answer:
The common belief in multiple gods shared by people of the world's first civilizations is known as polytheism, which includes religions with several deities each having unique attributes.
Step-by-step explanation:
The belief in multiple gods, as was common in the first civilizations of the world, is known as polytheism. Polytheistic religions center on a group of deities, each with unique responsibilities, personalities, and capabilities. An example of a polytheistic religion would be the ancient Greek religion, where gods like Zeus, Athena, and Apollo each played different roles within the pantheon. Polytheism stands in contrast to monotheism, the belief in a single deity, which characterizes religions such as Christianity, Islam, and Judaism.