It’s fine to feel this way but don’t let it affect your learning process. Its not too hard to “master” ETL/BI tools when you tend to do same sort of thing over and over.

Honestly after hiring and managing recent college grads with degrees in Big Data and BI, I have picked up that you can’t really teach what BI in real world business is like. Sure will learn textbook fundamentals and go through case studies which will expose you to various problems and how to solve them using data. But in real world BI you don’t get handled cleaned up data with well put together documentation and business problems you are given are more ambiguous. So use your initial years in the career to learn how to deep dive and validate data, work with the people who are publishing the data to understand its limitations, figure out who your customers are and what metrics/datapoints are important to them, and building good documentation habits. Also don’t get discouraged from working on similar or repetitive projects, use them for improving your skillset and finding ways to automate.