If "cheerful" means that someone is both happy and interested in people around them, what David Hume wrote is quite right.
But "cheerful" can mean something very different. It can mean a sort of mechanical bluff jokeyness, which has nothing to do with being a happy person, or with being interested in other people, except as audience or butts.
As a performance, that can be quite entertaining for a while. But in real life it can be very difficulty to take for long. It's worth noting that many comedians aren't too easy to get on with, and are sometimes very unhappy people.