What was Zeus' contribution to mankind?

Answer 1

Zeus played a dominant role, presiding over the Greek Olympian pantheon. He fathered many of the heroes and was featured in many of their local cults. Though the Homeric "cloud collector" was the god of the sky and thunder like his Near-Eastern counterparts, he was also the supreme cultural artifact; in some senses, he was the embodiment of Greek religious beliefs and the archetypal Greek deity.
Aside from local epithets that simply designated the deity to doing something random at some particular place, the epithets or titles applied to Zeus emphasized different aspects of his wide-ranging authority:

• Zeus Olympios emphasized Zeus's kingship over both the gods in addition to his specific presence at the Panhellenic festival at Olympia.
• A related title was Zeus Panhellenios ('Zeus of all the Hellenes'), to whom Aeacus' famous temple on Aegina was dedicated.
• As Zeus Xenios, Zeus was the patron of hospitality and guests, ready to avenge any wrong done to a stranger.
• As Zeus Horkios, he was the keeper of oaths. Exposed liars were made to dedicate a statue to Zeus, often at the sanctuary of Olympia.
• As Zeus Agoraeus, Zeus watched over business at the agora and punished dishonest traders.
• As Zeus Aegiduchos or Aegiochos he was the bearer of the Aegis with which he strikes terror into the impious and his enemies.Others derive this epithet from αίξ ("goat") and οχή and take it as an allusion to the legend of Zeus' suckling at the breast of Amalthea.
• As Zeus Meilichios, "Easy-to-be-entreated", he subsumed an archaic chthonic daimon propitiated in Athens, Meilichios.
• As Zeus Tallaios, or "Solar Zeus", he was worshiped in Crete.

**taking from Wikipedia**