"I Love Rock N' Roll" is a hand-clapping, drum-pounding, guitar-heavy piece of classic hard rock, and Joan Jett's cover of the song was one of the most successful singles in history. The song in some ways perfectly represents Joan Jett's identity in popular culture. She's the iconic example of a female rock lead, and one of only two women to be named among the 100 greatest guitar players ever by Rolling Stone.
Joan Jett described her first band, the Runaways, as "probably the biggest influence on female rock and roll musicians that there will ever be" (source) and her website says she has "spent her lifetime breaking barriers and challenging expectations."
"I Love Rock N' Roll" was her biggest breakthrough and remains her signature song, not least because of the topic it addresses so directly: It's a song about a girl who loves to rock out, plain and simple. The fact that she's singing it makes an implicit statement about gender, and it also exemplifies Jett's musical style, an accessible, slightly poppy form of punk rock.
Joan Jett doesn't buy either the "punk rock" label or the "pop" label: "I consider us to be a rock and roll band...straight down the line. I don't give a damn about my bad reputation, fake friends, sycophants," she says. "Oh yes, our music is rebellious in the traditional sense á la Chuck Berry, Elvis, these people are our idols." (Source)
For her, it's all about the music, and it wasn't until later in her career that she started speaking out about politics (she is, for example, an avid vegetarian and a somewhat open lesbian). The media continues to chase her with labels (Is she a bisexual? A feminist? An activist? A Democrat?), but "I Love Rock N' Roll" is a song about Joan Jett's more straightforward ethic: She's in it for the music, the adventure, and the pure unadulterated love of rock and roll.