This is the core character save file. It stores your character's stats, skills, inventory, stash, and quest completion data. Without this, your character does not exist.

Each character's data is split across several files, but the

Because offline save files are stored locally, they can be modified by third-party tools to enhance your single-player experience. Hero Editor

Keep separate folders for LOD and Resurrected. Even if the names are the same, the internal data differs.

Copy all extracted files with the character's name.

Diablo 2 Lod Character Save Files Link