So was every religion known to mankind. Yes, that means deities were made up so that humans could cope with death and make up answers to fill in the gaps on things that in truth, cannot be answered until science discovers one.
Religious beliefs, spirituality, and the need to worship a deity of some kind are undoubtedly durable traits. Some gods were worshipped for very long periods and then virtually disappeared from the historical record. For example, the sun god Ra was worshipped by many different cultures for thousands of years and then completely disappeared. If historical precedent holds, many of the gods worshipped today will be forgotten and quickly replaced by others.
During the past few years, neuroscientists have developed an area of study called the neuroscience of religiosity to understand the neurobiology of this fascinating aspect of human behavior.