I have ruled that any intelligent creature can use magic items when they follow the rules on understanding/attuning to them and have the reasonable physical capacity to wear it. So yes, an intelligent bear or wolf or ape could wear a cloak or a necklace or a crown, provided that they could manipulate the clasps properly.
As for Druids, magic items shape-shift within a range, so armor designed for a humanoid won't fit on a bear and armor designed for a bear won't adjust to a human, but a choker or belt may, depending on how much of a chance you undergo, so, a belt on a gnome might break when it turns into a bear, but a belt on a half-orc or a dragonborn might not.
Weapons are unusable unless you have the appropriate appendages to use one. So if you turn into an ape, you can still wield a sword. But if you turn into a bear, you cannot.