1930s? Well, they could be lots of things! Is your setting urban or rural?
Anyway - they can be factory workers, railway employes, aerospace engineers and airplane builders, they can be lab techs, they can be office workers. They can be department store employes, they can be newspaper hawkers, they can be farmers and street vendors and barkeeps and waitresses, actors, singers, sailors, bakers, cooks, telephone operators, etc.
Really, most jobs we have today they had in the 1930s - the level of technology was just different than we have today. Some jobs have disappeared, but honestly, you can just make up a character to suit your story and unless they're, like, an app-developer or an IT-tech, I'm pretty sure they have a job that existed in the 30s.