@vasilis I know one thing I was never taught at school about careers is the sheer variety of roles there are in companies.
For example, you could sketch out the variety of roles it takes to run a SaaS company: front end dev, back end dev, devops, QA, PO/PM, UI, UX, scrum master. Maybe data science/machine learning. Account managers/customer service/sales, marketers, data/business analysts, legal, finance, ... I'm sure there's more.
I know 16 yr old me would have found that useful.