How was jessie created for the toy story films?

Quick Answer
Jessie was created by Pixar’s creative team: the idea was suggested by Nancy Lasseter, and John Lasseter together with Pete Docter, Ash Brannon and Andrew Stanton developed and designed her character.
Explanation
The character of Jessie first appeared in Toy Story 2 as a rag‑doll cowgirl. The concept of adding a female protagonist to the franchise was suggested by Nancy Lasseter. John Lasseter, along with writers and designers Pete Docter, Ash Brannon, and Andrew Stanton, worked together to develop Jessie’s personality, appearance, and back‑story. They crafted her as a lively, brave rag‑doll who had been abandoned after growing out of her original owner’s hands, giving her a history that resonated with audiences.
Jessie’s voice was provided by actress Joan Cusack for the films, with Sarah McLachlan singing her parts in Toy Story 2. In video games, the character is voiced by Kat Cressida. The character’s design is a blend of western cowboy aesthetics and a worn, patched look that reflects her past as a forgotten toy.
The collaborative effort behind Jessie’s creation reflects Pixar’s emphasis on inclusive storytelling, ensuring the Toy Story universe represented both male and female toy characters. The character’s subsequent appearances in Toy Story 3, Toy Story 4, and the upcoming Toy Story 5 demonstrate the lasting impact of the team’s original development work.