Success at school, and in life, can seem like something that everyone else has got figured out and that you're the 'only dumb one in the village' who hasn't.
The reality is that success doesn't come easily to anyone. Success (and let's talk learning success here) is a hard road that kicks your bum and makes you feel dumb a lot.
Check out this Iceberg to help you understand how success actually works.
Also, understanding how your brain works is also a huge help to making sure your time at school is more successful.
Understanding how your brain works is crucial to bettering your learning. By understanding that learning is creating networks of chemical links between your brain cells, you'll understand that you're working better when something challenges you, when you don't get it the first time, when you forget after a couple of days and your teacher asks you to try and remember. You'll also understand that learning looks, feels and works differently for everyone. So you're perfectly normal in your own way. Check out some of these videos on how the brain works.
Really good learning involves testing yourself on what you know and what you don't know so that it goes from your short term working memory (that only holds about five things in it at any one time) to your long term memory where it is easily found when it's needed.
Check out these ideas on how to study better.