Why Medieval Era?

 

Actually it wouldn't really make a difference moo

If they can strike down a bigger and stronger guy whose job is fighting and which has much more experience than them I don't see why they can't pull out a jhon wick and steal the gun/phaser and stun the sci-fy mob moo
That would be interesting moo 

If the author suddenly said that the main character made a [Handgun] from memory, then it just doesn't make sense, because why would he start at modern weapons. He should've at least first tried making the earlier guns, like muskets and etc, because they are at least simpler to reason with than a freakin' [50. Cal]! 

Dr. Stone (manga/anime) does this btw 

I rather like the sword and gun combination, and magic pairs best with a staff. 

I got the answer as simple as possible when I tried non-medieval fantasy. Starships make magic useless unless you're super powerful magicans. Even if those starships are powered by magic. The more technology goes on, the harder it makes logical for one person to take everything in their hands. 

While not isekai, DanMachi is an interesting take on the Middle Ages setting trope: We have a mix of European and Asian-inspired characters and names. 

@Bad Storm why you no respond to mine, pls?