>>149988984
I think pretty much every TTRPG DM under the sun has a story where the players didn't care about the main NPCs the DM put actual effort into preparing, but they instantly fell in love with Boblin the Goblin because he talks funny.
It's often the result of a "caring quagmire": If you really care about getting something right, people can smell the stiff tryhard-ness from a mile away. But if you think it's just gonna be an inconsequential one-off, you'll be much more open to wit, interpretation and improv.