I don't think there is any way to skip the sword for the simple fact of our limited health, damage boost doesn't last long enough and also the cellings in the rooms for blue key are too low to be able to say spin jump on the spiny in the room however if there was a way to get past the first couple of spiny then it might be possible

In the case of new categories we are limited by the content in the game not being a lot. Now as you said this could have been different if the sequel or even deluxe versions came out but those haven't been updated in years and likely won't be. Although I'm sure someone could try reaching out if possible

Well I guess it was only a matter of time