Courage is a synthetic emotion that is a combination of fear, and love or hope.
The opposite emotion of fear is courage.
Courage is to overcome fear by suppressing it and taking action. There is no courage without fear. To feel absolutely no fear is not courage. Courage is being aware of fear but not taking action based on fear.
The reason we need courage is because as human culture developed situations in which fear is not an adaptive response increased. It is more dangerous if a person who encounters a bear just cowers in fear, even though the person has a hunting riffle.
There are two kinds of courage, courage with hope (self-confidence) and courage with love. Courage is not a specially fixed emotion, but is fear plus hope or fear plus love.
Acrobats do not fear heights when they walk a tightrope, this is because they have confidence to succeed, courage from hope.
For example a parent jumping into a river to rescue their child is courage from love.
We call it courage when a situation is scary and love or hope overcomes the fear. So without love or hope there is no courage. The strength of courage is in proportion to the strength of love or hope.
In an old book from China, the Analects of Confucius, it says, "a benevolent person is brave, but a brave person is not necessarily benevolent." This means that all people who are truly compassionate towards others can act with courage, but a courageous person is not necessarily compassionate.