Of course medical knowledge went down. Now that there is no war people no longer get hurt or suffer diseases...
FMC kick was enjoyable though. If anything saves the chapter it would be that as it is rare to see the female counterpart take the spotlight in these situations. Just a shame that the world building is so terrible.
It could've been an immesurable time later and the FMC could easily join the party by being saved after his rebirth, but that wouldn't be anything new or special so i get why author wanted it to be a relatively short period. That being said you just can't have your cake and eat it too. Magic could've gone a different direction instead of just regressing and MC could have had some wonder about these new concepts that he either never considered before or simply didn't have the time to spend on them, instead of this bored of life child-man we have now.
Quite possibly my biggest issue with this could be MC looking bored in every panel, he never gets angry or happy.
Anyway rant over for now and yay FMC.