Ditto!
Watched 2001:A Space Odyssey last night. Haven't watched it in a while. Still have no idea what it is about.
Alas...
OK, here goes.
<Carl Sagan voice>
Billyuns and billyuns of yeers ago, billyuns and billyuns of light yeers away,
</Carl Sagan voice>
a civilization developed FTL flight and communications and began to explore the galaxy. Eventually they found Earth, which was inhabited by various species, including an upright bipedal social group with potential to develop intelligence and, eventually, their own space flight etc.
This species, however, lacked three things, none of which were possible in the ordinary course of events without at least one of the others. The proteins in meat necessary for brain development beyond their current level; the knowledge to use tools/weapons to obtain the meat; and the appetite to want to eat the meat.
The advanced civilization noted that one of at least two groups of this species had the best potential for taking advantage of any help given; this group had recently been chased away from "their" source of water by the other group, who (since they lacked weapons or the knowledge to use them) used intimidation and numbers to accomplish the task.
The advanced civilization sent three devices into the Sol system. One, placed near the cave that sheltered the "chosen tribe" of upright bipeds, which transmitted information to their brains (use tools to kill, eat the meat, it's yummy). The second, buried Tycho crater on the Moon, when exposed to sunlight transmitted "they found me" toward Jupiter. The third, in orbit around Jupiter, had two functions that we learn about in
2001 (two other functions are found in the sequel,
2010); Receive and relay "they found me" to the host civilization, and serve as a hyperspace portal to a location, possibly the host civilization's homeworld.
The bipeds learned to kill and eat meat, and simultaneously to use the weapons to retake "their" water hole. The opposing group suffered one fatality, probably their leader, in this first of many human battles. In an iconic sequence, the triumphant leader of the victorious group flings his bone-club into the air, and we jump-cut to Earth orbit in mid-1999 and see orbiting weapons platforms, a space station, and a commercial shuttle ("Pan Am").
The device in Tycho had been found and an excavation made around it. Due to the length of lunar "night", the sun had not yet shone on it properly (apparently, directly overhead). The head of the US space agency and others stations on the moon visited the device just at sunlight reached the proper point. The device sends its signal; it was audible as a loud screech on the mens' spacesuit radios. It was determined that the message was sent towards Jupiter.
Eighteen months later, in 2001, USS Discovery was en route to Jupiter to investigate. Three scientists were put aboard in hibernation, while the pilot and copilot were conscious and kept unaware of the nature of the mission. The on-board computer, which was either sentient or capable of simulating sentience (it could make autonomous decisions and operate the ship without human input) was aware of the true mission, but programmed not to reveal it to the conscious crew. This created a logic fault in the computer, which attempted to kill the human crew; it succeeded in killing all but the pilot, who disconnected the higher logic functions and found the recorded mission briefing from the space agency head.
The pilot continued the mission, finding the third device in Jupiter orbit. Its function as a hyperspace portal activated, and he was carried off to seemingly live the rest of his life in a bad copy of a luxury hotel suite. He was apparently under observation, given the whispers and noises heard in this portion. Eventually, seeing yet another of the rectangular devices at the foot of his "deathbed", he apparently dis-corporated and returned to Earth as a higher-order being (resembling an unborn baby), and as an observer. There are mentions in the literature of his proceeding to detonate (harmlessly) the orbital weapons, but I don't see that in the film, nor is it mentioned in the sequel.
"TL/DR!!" Amirite?