It seems like everybody already knows everybody else, and you don't know anybody. Chances are, they aren't trying to scare you. They probably will make great friends. Don't be shy and hide, because people won't notice you. Or worse, they will think you are rude and aloof.
Some teachers tend to be less harsh on the first few days, and some are a bit stricter.
A teacher who seems mean might just be strict. The best way to deal with a strict teacher is to find out exactly what the rules are, then follow them. Your teacher probably won't mind if you ask after class how they feel about talking in class or late homework. It's better to find out right away and follow the rules than to find out after you've broken them. If you are struggling with your homework, talk to your teachers about why you have trouble getting it done.