Liberal thought is all about seeing people as individuals. You become a liberal when you learn to see past group affiliations and notice in everybody one single human being whom you equate to yourself. This is liberalism: everybody is a human being whose value is equal to myself.
This way of seeing the world has its negatives and positives. In its extreme form it gave us neoliberalism which I hate. But liberalism (as opposed to neoliberalism) is the greatest advance of humanity ever, in my opinion. And it has transformed the world for the better since it came into existence.