Arduino's (the company) goal is to make microcontrollers accessible to everyone, not just engineers! So if you just use their IDE and software library you don't need to be concerned about anything within the board, just the terminal blocks at the periphery. Being an Electrical Engineer, and having spent decades teaching (part time) electrical engineering students, I ended up writing a series of books that delve into the workings of the microcontrollers in Arduino boards and how the Arduino software library presents or hides the features. The titles all have "Far Inside The Arduino" as part of their titles and can be found on Amazon. If you ever want to get into this deeply, look them up!