If it walks like a duck and talks like a duck it should have a duck interface
Once again, a lot of my confusion here comes from not knowing what exists in a particular language and what is just an academic term for a system that arises from your code.
Okay, I now get what you mean: Linked Lists Are Not Things. They are not integers or objects.
One of the early things you learn in an oop language is to make you own linked list, and then you learn to forget about making your own because people smarter than you have made one for you already, and that (here it comes)
implementation of a linked list is useable as if it's an object. This also goes for vectors, maps, etc. In some languages even for strings. It's like you said: a construct. BUT most languages have already an implementation of that construct in their standard library. Some have more, for instance Java has a "List" interface, with two implementations, ArrayList and LinkedList. Both act exactly the same, so they are completely interchangeable, except that one is faster at searching and the other is faster at adding/deleting, so which one to use is up to you at that moment. Nothing is stopping you from writing your own unique implementation, though.
tl;dr: So, in short, (for Java and the C's at least) the library has stuff (like maps and lists), that are merely pieces of code written by our betters[1], they do not "belong to the language".
[1]Well, except for the guy who made the standard list implementation for haxe. He was on crack.