Created
Often represents when the current file record was created. Copying or restoring can make it newer than the original content.
Modified
Represents a content-related change, but applications and metadata workflows can update it.
Added or downloaded
Can reflect when an item entered a location, not when its content originated.
Access-related dates
May be unavailable, disabled, or updated differently by the file system and application.
Cloud synchronization, archives, migration, backups, and imports can rewrite dates. Use them with path, content, ownership, and backup information.
“Old” is a review criterion, not a determination that a file is unnecessary.