To shape this round into Nirvana, firstly listen to Bleach. You can hear the Black Flag influence on there as well as other things such as Swans. That martial beat on Papercuts is very reminiscent of Swans in my opinion. Kurt Cobain was gifted/cursed with writing very accessible music (if you compare it, say, to the roughshod output of the Meat Puppets who often sounded drunk at the wheel) and he was also very self conscious. Nirvana were elevated well out of the petri-dish of the underground music scene they had tried to be a part of so they had the unique position of gaining megabux from slowly becoming the figureheads of a music scene that largely didn't exist (Grunge was a media/fashion construct) and risking mass-ostricision from the smaller underground scene they had been part of.