There is no universal folder that is always safe to delete. A safer question is: who owns this item, can it be recreated, and do I have a recoverable path if I am wrong?
Usually worth reviewing
Old installers, known duplicate downloads, and app caches can be candidates for review. But even cache folders can contain session state or offline work, so confirm their purpose first.
Usually leave alone
Unknown system folders, files used by current projects, backups you have not verified, and data you do not recognize should stay put until you understand them.
A careful next step
Use this guide to understand the storage you see, then make changes only after reviewing their purpose. DiskClue can help make the evidence easier to inspect in the current MVP.
Understand your storage with DiskClue →