A few years ago I was just getting started learning Drupal 8 and decided to try to play around with the Twig theming templates. I barely understood Drupal at the time so that was a bit of a mistake. Not really understanding what I was looking at meant that I was overwhelmed quickly by the number of files and not understanding what I was looking at inside of them. I soon realized that if I was going to work on a theme, I needed to try to understand Twig, but without the complexity of Drupal surrounding it.