[Machette]

Human Evolution
Technology
Artifical Intelligence
Extra-terrestrial life


Kubrick, however, said "You're free to speculate as you wish about the philosophical and allegorical meaning of the film—and such speculation is one indication that it has succeeded in gripping the audience at a deep level—but I don't want to spell out a verbal road map for 2001 that every viewer will feel obligated to pursue or else fear he's missed the point."

That's the great part about the movie.