Kubrick and Clarke wrote the script based on a short story called The Sentinel and Clarke went on to write the novel - while the film was being made. The ending doesn’t have to show that man has progressed to a state beyond war. It’s implied. There is no reason to make that concrete.
Right.
Because an incomprehensible psychedelic experience followed by a giant baby floating in space just screams that conclusion.
Right.
QED.