It's 1/3 about a normal guy who's entirely burnt out with his job, and 2/3 capitalist propaganda about how trying to change careers is a devastating life choice and trying to implement socialism will ultimately fail.
(Act 1: Burnout) Meet Jack Skellington, a faithful, overworked regular guy with a useless title that means more responsibility and no perks. We have no idea how long he's been in this role, but we get an idea that he's pretty good at it. He never seems to miss a day of work despite how much his job is draining him. Throw in government bureaucrat who starts demanding he return to work immediately after his busiest night of the year. Mr. Mayor has never done the job of Pumpkin King, but has plenty of tips on how Jack can improve. Also introduced in in Act 1: loyal puppers who is his main relief in life and girlfriend who is a literal slave to the old powerful man because he “made her who she is today” so she's bound to never escape his grasp. Background cast: Clueless employees who have no desire to question the status quo. Jack decides to take a day off of work to deal with his mental health and the entire corporate regime of Halloweentown loses their ever-loving mind. On his day off he discovers a new lease on life that he didn't even know existed due to the constant demands of his job. End Act 1.
(Act 2: Career Change) Jack, after a successful mental health day, returns home. He's excited about his future and ready to get started in a new role. After literally everyone harasses him about the work he's missed while gone, they then start gossiping about how odd he's acting for wanting to do something other than his current role. Also, the only way for him to achieve this career change is to literally hire some goons to kidnap the beloved CEO of Christmas Inc., who has selflessly been doing that job for centuries. End Act 2.
(Act 3: Jack Sucks/Socialism is bad) Jack fails miserably at his new job. Major drama goes down involving a call to the police and attempted murder of Jack. Nothing to see here. Just the cops doing what they do best… Using force to push down those they don't like. How dare Jack make a try at a job that involves kindness and giving to others instead of terrorizing those beneath him. Only the crusty old CEO of Christmas Inc. can save the day in the end. The guy with no job and no real purpose is the epitome of all evil and looked down on by everyone. Moral of the story kids? Never try to rise above the station WE'VE determined you belong in, no matter how miserable you are. You don't really deserve a promotion… Also, sure, socialism works for those guys over there, but it'd never work here and how dare you try to implement a new system. Your job is to scream and growl at children and then laugh about it with your buddies. Work hard your entire life, and never retire. Look at Oogie Boogie. He doesn't work and the world hates him. Movie ends with Jack happily returning to the job that just made him miserable an hour and a half earlier. At least Sally is free though. Someone finally talked to HR about it and they needed a gesture of good faith to prove they're on the working (wo)man's side.
In hindsight maybe its 100% capitalist propaganda. Sure they showed him depressed and burnt out, but ultimately all he needed was a change in perspective to become a model employee again.