That is kind of true. Everyone in Springfield is some wacky over the top character that is usually a loser of some kind, or a fat slob. Then you have Lisa. She really does not fit into the setting at all.
Everyone else is a sloppy drunk, corrupt businessman, has-been tv personalities, chronically out of work losers, trouble causing church people, fake doctors, comedy mafia, completely aloof school staff, and various cultural parodies with the scotsman, sea captain, bee man, italian chef, japanese karate intructor, etc.
And then there's Lisa. It's like she comes from a totally different show. She is more like a smug, cartoonishly liberal knowitall King of the Hill antagonist of the week. Who is only capable of spouting random liberal talking points or looking down her nose at anyone who does not think and act exactly like her.