I was super excited to play this when I read the description , it instantly reminded me of Rollercoaster Tycoon and Planet Coaster and it's a pretty brilliant idea to hone in on the scope of one ride. Sounds like a solid hook to me.
The audio definitely reminds me of those old games, especially RCT. It's simple, but nostalgic.
I love the art style of the mascot and the UI. The art style kind of reminds me of 90's cartoons, while the UI reminds me of Please, Don’t Touch Anything. The format of looking through a monitor also conjures up feelings of a horror game like Five Nights at Freddy's. I'm not sure if that is what you're going for but the console terminal with the masked mascot makes it feel slightly eerie (that and I keep killing passengers on the ride by accident lol).
I can see potential in the gameplay loop. It feels like the seeds of something that could be hectic and fun where you're keeping spinning plates in the air; it seems chill at first, but becomes more challenging as you progress. It feels like it could be a rollercoaster, Papers Please.
That said, the current state of the gameplay loop is more frustrating than fun. The fundamental problem seems to be that you can only go as fast as the first car. If the first car is a snail, any cars behind it can't go faster unless you wait a significant amount of time. This could be interesting since as you wait, the line gets longer; but I think you'd need to make the rollercoaster shorter so that waiting is a more feasible strategy.
Perhaps start with a very simple rollercoaster (like a kiddy coaster with that goes in one loop) where you can see at a glance how long it will take for cars to finish, then gradually make the coasters more and more complex with each level passed.
There also need to be some meaningful stakes involved. Right now nothing bad seemingly happens if the line gets too long or if you don't cater to customers needs. I tested it by setting all cars to speed 1 and never letting anyone new get onto the ride, I also intentionally crashed several cars and still ended up with a score of 1400 and "your customers were happy".