has anyone sang a cover of it?
Yes, American country duo Bomshel,  Japanese singer-songwriter Kaela Kimura
Cover versions and other usage
American country duo Bomshel included a cover of "Just a Girl" on their 2009 debut album "Fight like a Girl". JC Chasez's girl band Girl Radical recorded a cover of "Just a Girl" in 2013, which served as their official debut single. They filmed a corresponding music video for the song which was released on August 15, 2013. On a 2017 episode of "MTV Unplugged", Japanese singer-songwriter Kaela Kimura covered "Just a Girl" live as the seventh song of her 14-track set list.

i'm just a girl by no doubt "Just a Girl" is a song by American band No Doubt.
Yes, Bomshel and Girl Radical recorded a cover of it. Yes, Bomshel, Girl Radical, Kaela Kimura, Pink and others. Yes, American country duo Bomshel included a cover of "Just a Girl" on their 2009 debut album "Fight like a Girl".
Just a Girl Just a Girl Just a Girl
Cover versions and other usage Cover versions and other usage Cover versions and other usage
American country duo Bomshel included a cover of "Just a Girl" on their 2009 debut album "Fight like a Girl". JC Chasez's girl band Girl Radical recorded a cover of "Just a Girl" in 2013, which served as their official debut single. American country duo Bomshel included a cover of "Just a Girl" on their 2009 debut album "Fight like a Girl". JC Chasez's girl band Girl Radical recorded a cover of "Just a Girl" in 2013, which served as their official debut single. They filmed a corresponding music video for the song which was released on August 15, 2013. On a 2017 episode of "MTV Unplugged", Japanese singer-songwriter Kaela Kimura covered "Just a Girl" live as the seventh song of her 14-track set list.

In 2018, Pink sampled "Just a Girl" and Nirvana's 1991 single "Smells Like Teen Spirit" during performances of her singles "Just like a Pill" (2002) and "Who Knew" (2006) for her 2018–19 Beautiful Trauma World Tour.  American country duo Bomshel included a cover of "Just a Girl" on their 2009 debut album "Fight like a Girl". 
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Just a Girl [SEP] Cover versions and other usage
American country duo Bomshel included a cover of "Just a Girl" on their 2009 debut album "Fight like a Girl". JC Chasez's girl band Girl Radical recorded a cover of "Just a Girl" in 2013, which served as their official debut single. They filmed a corresponding music video for the song which was released on August 15, 2013. On a 2017 episode of "MTV Unplugged", Japanese singer-songwriter Kaela Kimura covered "Just a Girl" live as the seventh song of her 14-track set list. In 2018, Pink sampled "Just a Girl" and Nirvana's 1991 single "Smells Like Teen Spirit" during performances of her singles "Just like a Pill" (2002) and "Who Knew" (2006) for her 2018–19 Beautiful Trauma World Tour.