Eliezer, I think your proposed semantics of "ought" is confusing, and doesn't match up very well with ordinary usage. May I suggest the following alternative?

ought<X> refer's to X's would-wants if X is an individual. If X is a group, then ought<X> is the overlap between the oughts of its members.

In ordinary conversation, when people use "ought" without an explicit subscript or possessive, the implicit X is the speaker plus the intended audience (not humanity as a whole).

ETA: The reason we use "ought" is to convince the audience to do or not do something, right? Why would we want to refer to ought<humanity>, when ought<speaker+audience> would work just fine for that purpose, and ought<speaker+audience> covers a lot more ground than ought<humanity>?