ERode, the school doesn't teach only combat. Some people come because they're already good at that, but need to learn the other parts of being a Dawn Slayer or just have an environment that allows them to meet with people in a caring environment. 

Not all the staff, for example, are good at combat. If we threw Ninja Janitor and Aram vs Deja or maybe Alice, I'm pretty sure Deja or Alice would be well within her power level to win that fight. Aram and Ninja Janitor are not super combatants. They aren't helpless and know how to handle themselves, but they aren't warriors.

So, I'm betting some of the second/third/fourth years will totally be super awesome better than us. And some of them will be specialists in other fields, who aren't all that great at combat.

In other words seniority =/= power level.

The hall monitor Val, for example, is likely several times more powerful than Rachel the Vice President.