The Discworld books are light, easy to read, and funny. They generally start out with a bunch of jokes about stock fantasy tropes and modern society, but they get less jokey and more serious (not incredibly serious) once you get attached to the characters and invested in the plot of the book. Then they become well written but fairly standard internal/external plot stuff, but you like all the characters because they made you laugh when you met them, and the actual meat of the plot is something new because it started out as a joke.

I’d start with Mort, but you could start with any sub-series and have a good time. (Though the early books starring Rincewind aren’t as good as the rest. )