The liberal arts originate in Greece, specifically Athens, during the time of its democracy. They were the arts appropriate for the free person, as opposed to slaves. Slaves took care of the "mechanical" arts, the ones related to providing for physical and social needs. Many slaves were very skilled at running businesses, manufacturing things, and so forth.
So, were the liberal arts the useless arts? No. They were the arts related to democracy. While slaves could do many things, they could not speak in the Athenian assembly. That was reserved for citizens. The liberal arts prepared a person for citizenship, that is, expressing oneself well, making good decisions about public life and the direction of the city, being able to tell truth from falsehood, knowing what to believe and why, deciding on court cases.
In other words, the liberal arts were the arts that prepared a person for involvement in civic and moral life. There were no universities in Athens at the time, but there were schools that claimed to do this. Plato's Academy and Aristotle's Lyceum were two that taught the liberal arts in this sense.
There were other places you could go to learn and apply a watered-down version of the liberal arts. Plato criticizes the sophists, essentially the lawyers of their time. They would argue any case you needed them to. They were seen as having abandoned the spirit of the liberal arts, since they were using the skills of the liberal arts without the accompanying search for truth. They just advanced individual interest.