No, 'I Am All Girls' is not based on a true story. It's a made-up narrative designed to engage and captivate the audience through fictional elements and plotlines.
It could mean that the speaker is the entirety of a story related to girls. Maybe it implies that the person is central to all the experiences, events, and emotions that are typically associated with girls.
I'm not sure specifically what 'i am all girls real story' is about without more context. It could be the real story of a group of girls, perhaps related to their experiences, dreams, or challenges they've faced together.
It could also suggest that the individual is representing the essence of all the true stories that girls have. It might be used in a context where the person wants to convey that they understand and can speak on behalf of the real - life events, emotions, and challenges that girls encounter in different cultures and societies.