Yes he did, but I'm not sure how that relates in any way to anything I said. His message idea were based on how cells communicate via messages in biology. Objects are cells. As I ran a popular Smalltalk blog for a few years, I'm well aware of Kay and the history of Smalltalk and his intentions about messaging.

No, that's the birth of objects, objects and object orientation are entirely different things. Objects are an abstraction, Smalltalk did not invent them; Object orientation is a description of a programming style; Smalltalk invented that. Alan Kay absolutely invented object orientation as he coined the term which means taking objects and basing the entire language and programming style on them, i.e. the language is oriented towards them to support the object as primary abstraction style.

Simula had objects, but it was not object oriented, it was still a procedural language; objects were bolted onto procedures. Smalltalk was the first object oriented language, objects are the means of abstraction from which the entire language is built; that's what object orientation is. The term object oriented and thus OO was never uttered before Smalltalk and thus Kay made up the term and is the inventor of the OO style of programming.