Whether it’s a chairman or a chairwoman, that person is in the seat of authority and has been since the fourteenth century.
At that time a chair was a throne, it came from the Greek word ‘cathedra, leading to the word cathedral for the place housing the seat of the bishop.
In business, the person in charge sat in a comfortable armed chair, while everyone else sat on stools, and so he took the esteemed title “chairman.”
So the presiding officer of a committee is called a “chairman”.
