Good to see the kids holding their own here, it would have kinda broke the power scaling if they won on their own after 1 day of training, but I do think this did a good job of setting up and letting them show off their new skills and power, signalling that there will be more to come and that while MC will always be at the top, that the others will get their time to shine even if it is thanks to him. They might not have killed the demon, but I would say this chapter made clear they 'won' in this race against time, not just survived but actively won, which goes a long way to giving these kids an active role in the story even from step 1 I think.