father: the man who begets a child, and by extension anyone who stands as a father to others
At its root the word names the man who fathers a child, and most of its more than a thousand uses are exactly that everyday sense. But Hebrew lets the same word reach backward and outward from that center. Looking back through the generations, a father's father and the line of forebears are all called by this one word, so the plural "fathers" usually means ancestors rather than living parents.
Looking outward, the word names anyone who fills a father's role for someone who is not his own child. The man who first does a thing or founds a line or a town is its father; the protector of the helpless is a father to them; a counselor to a king, a revered prophet, or a priest is addressed as father. In each case the point is the relationship a father has to those in his care: he gives them life or standing, he provides, he protects, and he is owed honor.
From this the Bible takes its boldest step and calls God the father of his people and of the king. This is not one of several unrelated meanings but the same idea stretched to its limit: the one who gives Israel its life, guards it, and claims its loyalty. Reading the word always means asking which of these relationships, biological or extended, a given verse has in view.