PC Gaming

"...completely different ideas of the word medieval."

That is likely due to our staggered familiarity with the games, which you haven't played. Your screenshot is from one of the areas outside the collapsed castles and cities, without any narration or dialogue, and is consequently non-representative of the setting and atmosphere.

Bearing in mind that medieval only refers to one aspect of the setting mentioned above, it's an accurate descriptor for Hollow Knight and Silksong: Medieval refers to the time after the bygone era of royal society, fallen castles and a decimated population left behind after the apparent invasion and collapse. Even in your screenshot early on in the game, you can see evidence of some higher society collapsed by that gilded metal.

The Hollow Knight games are all about a wandering knight/warrior returning long after the collapse, working their way up to a central castle structure, "The Citadel". What used to be a thriving world and society with centralized authority has been reduced to destroyed cities and towns, abandoned, shadowy brick and mortar rooms and roads, some shuttered churches and scattered huts lit by candles. Evidence of grander past societal achievements are the physical setting of the game in the forms of great broken bridges, mechanical mechanisms that few are capable of operating or maintaining, and importantly to this thread, "the language aspects of medieval society" can be seen throughout all game text as anachronistic linguistic references to a bygone higher world, both structurally and socially.

"the characters don't even resemble humans!"

They are not humans, they are bugs, which is where the "fantasy" descriptor comes into play.

If you like video games, you should give HK or Silksong a whirl. They are great games and a lot of what I have had a very fun time describing will be both apparent and described in-game after you've spent time in their world.