Since we don't have more details, Kelly could be any woman. She might be a fictional character created for a story about birth in a city, or it could be a real person's experience that is being shared.
There were a few novels with female protagonists named Kelly, such as " The Founding of Africa,"" The Plump World Group Pet Kelly," and " The Plump World Doujinshi All Kelly." These novels described the love stories between Kelly and other characters. However, due to the limitations of the search results, it was impossible to determine whether Kylie was the main character.
I'm not sure exactly who Michelle Brown is without reading the story in detail. But she is likely the victim of identity theft in this particular account.
Kelly is the main character in this story. She is likely a person who has a weight problem, specifically weighing around 600 lbs, and the story probably focuses on her life experiences related to her weight.
I'm pretty sure there isn't a Michelle in the Spiderman comics. The comic characters are pretty well-defined, and Michelle isn't one of them. But you never know, there could be a new character introduced in future issues.
Michelle Brown is the victim of identity theft in this story. She is the central figure whose experience with having her identity stolen is being told.
I'm not sure specifically who Kelly is without watching the story. But generally in 'my 600 lb life' series, the person is someone struggling with extreme obesity and their journey to a healthier life.