Board Thread:Questions and Answers/@comment-25958552-20160731160314/@comment-29448669-20160805225138

There's no actual canon info. about the game to prove that humans got weaker after the barrier incident, even, Chara and Frisk are the only humans that can be seen on the game. After all, Asgore's intents were to not KILL. And also, if the humans were weaker after the "war", their souls would lose determination enoughly to be weak like monsters ones, and they would lose the ability to grant god power to the person who collected 7 human souls and one single monster/Boss monster soul and absorbed them.