Although bronze was the favored material for freestanding sculpture in greece, most bronze statues have not survived, because

Although bronze was the favored material for freestanding sculpture in Greece, most bronze statues have not survived, because they were melted down long ago to make useful objects, weapons, such as spearheads. The Charioteer (about 470 B.C.) is an example of the life-size bronze statue and it was discovered at the great sanctuary of Apollo at Delphi. 

Most bronze statues from ancient Greece are no longer in existence because bronze, unlike other media such as marble, was inherently valuable and recyclable into other items such as coins, weapons, and art. As such, invaders and occupiers in the centuries after the end of the Greek period looted and melted down nearly all ancient Greek bronze statues.

Ithink they was worshiped because they have big head and people worship who the biggest and have power that why