You can play this riff, as well as the entirety of the song’s melody on the xylophone, and it’s a good song for beginners with a little bit of experience behind them too.
Yet, the musicality is there, and its ominous quality lends itself to the subject matter of the song (which, admittedly, remains somewhat of a mystery). The brilliance of the main riff to Nirvana’s “Come As You Are” is that it’s almost like a beginner guitar exercise (which could be the case – you just never know where song ideas might come from).