You can find the .jar files for various Minecraft versions (e.g., 1.20.1, 1.21.1) on official sites like CurseForge and Modrinth .
If your goal is to "develop a story" using a physical "Story Jar" (sometimes called a "Story in a Jar"), this is a creative activity used to spark imagination. Tell a Story in a Jar! | Activity - Education.com Download Blueprint jar
If you are looking for the Minecraft technical library or mod: You can find the