Olives are inedible right off the tree
While technically you can eat olives straight off the tree, you don’t want to. Raw olives are extremely bitter and have very different textures than their cured counterparts.
Olive Oil Use
Olive oil was historically used for food, medicine, as fuel for lamps, to make soap and for skincare
Olives change color as they ripen
Olives start out green and as they ripen, they will change color from green to light brown to red or purple to a dark black.

The history of olive is much older than the human one.
It is known the legend that dates the appearance of olive to the conflict between Athena and Apollo regarding the name of the city of Athens. It has been recognised as the symbol of peace; it has been considered sacred tree and victors of Olympic Games were crowned with leaves of wild olive (“kotinos”).