You removed pretty much the entire draw function. That's why it doesn't work.
Plonker code for reference:
https://hastebin.com/zufitoziro.rb
Draw function: 183-237
Of note: I'm the weird person who's too used to Graphics.glDraw's family of functions to switch to using the Sprite class, because I find it easier to work with. Your mileage will almost certainly vary. The piece of code you didn't remove (the for loop) rotates four vectors (vt) defining the top left, top right, bottom right, bottom left corner of the drawn area (relative to 0,0) by the NPC's angle. The rotated result is (ought to be) later used for the vertices of the draw call (offset by the npc's pivot, so that it draws relative to the NPC, not 0,0).