The correct answer to this open question is the following.
The range of functions that people attributed to their most powerful god Indra during the Vedic Age was the following.
Hindu people believed that God Indra was the most important figure in the heavens. In the Vedas, Indra was the King of heaven and had powers over the lighting and thunder. His will could start storms and floods. Indra also was the king of war.
This concept of a divine powerful God can be compared with the role of other gods in other ancient religions such as the almighty god Zeus in the Greek pantheon or its similar God Jupiter in the Roman pantheon. Ancient civilizations used to think about heir gods as powerful divinities capable of the greatest deeds, and with total control over humans.