I don't think C++ is object-oriented, and it is certainly way less OO than Java in most ways. Its "classes" aren't the same kind of thing as classes in OO languages and its "objects" aren't OO objects.

In part this is because by default even C++ class instances don't have identity, or anyway they only have identity in the sense that ints do, that every (non-const) int has an address and mutable state. You have to define a destructor, a copy constructor, and an assignment operator to give identity to the instances of a class in C++.

With respect to "participates in a class hierarchy", that has not been part of the definition of OO since the Treaty of Orlando. But, in Java, all objects do participate in a class hierarchy, while no primitives do, while, in C++, you can also create class instances (or "class" "instances") that do not participate in a class hierarchy (without ever using inheritance, even implicitly). So, regardless of how OO or non-OO it may be, it's another distinction that Java draws between primitives and class instances ("objects" in Java) that C++ doesn't.

I think we are in agreement.

In C++, everything is an object as defined by the C++ spec, but a lot of things are not objects in an OO sense.

In Java, almost everything is an object in an OO sense, but some stuff is definitely not.