My devil system

in a normal world everyone is only looking our for there themselves the human suddenly gain abilities called system and with the system they were able to become stronger and smarter, after a while alien visited earth in hope to conquer it, it fuel a five century worth of war, both side suffer extreme lost to the point that they had to make a deal to not attack each other for a century. eventually the school was replace with training facilities, and the human began to slowly conquer the universe. The human even found an inter dimension place where monster exist and you can easily become stronger and human even started to make camp in the inter dimension and slowly started to conquer the place.