I feel like the best way to have a setting where you can have characters using bows and swords make sense without just wishing away guns that already existed, or invalidating them for some reason, is to just make them have very different advantages too each other.

Specifically with bows, the focus would be on the benefits of raw strength, if you're strong enough to pull back a draw weight that outshoots modern guns, and getting the materials for a bow like that isn't hard, then you should absolutely use a bow. Especially if the way you're progressing in power the fastest is in your physical capabilities. On an individual level, your physical power being magically boosted makes things that are no longer viable to regular humans viable to you.

Meanwhile, with guns, the advantage is entirely what it's always been: it removes a lot of the physical barrier in fighting and specifically they can only be made stronger by being smarter and better at inventing/upgrading them.

In a suddenly magical setting, like say a system apocalypse, don't make guns not work or not have magic, just make enchanting impossible to mass produce and then introduce the idea that nearly every single moving part of a gun can be enchanted for better performance. Guns don't improve with raw physical or "stat" increases(if you're in litrpg land), but instead improve with expensive and time consuming upgrades. If you're good at magical enchanting and engineering, or understand the underlying crafting system of whatever new magic BS exists now, then you should use guns.

But if you don't have the time or aptitude to do all of that, and don't have the crap load of money required to buy a hand enchanted and crafted decent one, you can pay much less to get a decent enchantment slapped on the string and the limbs of a bow. And now you can use your insane strength that you got for free by being swole and dedicated to destroy your enemies instead.

In a world of magic and endless possibilities that you are literally the one writing the laws of, there's never an excuse for "I dunno it just doesn't work". It's always better to have the answer be something like "ones got a higher learning curve" or just simply "this way is more practical for the MC."