When an Entire School Transfer to Another World, I got an OP System

Apparently, the entire school got summoned and transferred to another world by Gods. They were originally supposed to summon one person who would become a Hero, but they made a mistake. Moreover, the place where they summoned them was near a forest where monsters such as Orcs, Goblins, Ogre, wolves etc. reside. After encountering and defeating an orc, I found myself in a space where Gods reside. They explain the whole situation and request me to protect as many people as I can as they can't interfere because of restriction. In order to protect my childhood friend and many others from these monsters, I think about how to survive using the 'System', along with the blessing I received from the Gods. This is the story of my legend.