Most of those „rip offs“ are just pretty basic chord progressions that are quite common.
The rest i would maybe call „inspired by“ instead of rip offs.
Nirvanas songs are often simple and repetitive (not a bad thing!) and that leads to many possibilities for finding parts of songs from other bands that sound similar.
Their texts however struck a nerve during their time. That’s why they became a phenomenon.
I know. I just found this glorious as its full of other bands I love (and was basically raised by). A band without influences is destined to have no influence.