2001 was an important movie for me growing up too, and for the same reasons.
I even have a model of the orion III shuttle hanging in my bedroom with custom made Pan Am decals.
(the orginal Airfix kit couldnt use the PA logo, so a screen accurate version takes some extra effort)
The story was magnificent for its time, but sadly the movie didnt convey the idea very well. Most of the audience in the day came away a bit confused as to what had happened.
When i read the actual story many years later , the movie made sense.
The ET wanted to meet us, But rather than travel here. It instead uplifted us so we could come to it.
Thats what the first monolith scene is about. Thew apes touch it and are "upgraded" the scene where the central ape character throws the bone into the air cuts to a spaceflight scene. Its so simple and so elegant a visual way of conveying the idea. But again went right over the heads of the audience of the day.
Stanley Kubrick explains the meaning of 2001: A Space Odyssey - Flashbak
Clarke's novel as explanation
Arthur C. Clarke's
novel of the same name was developed simultaneously with the film, though published after its release.
[8] It seems to explain the ending of the film more clearly. Clarke's novel explicitly identifies the monolith as a tool created by
extraterrestrials that has been through many stages of evolution, moving from organic forms, through biomechanics, and finally has achieved a state of pure energy. The book explains the monolith much more specifically than the movie, depicting the first (on Earth) as a device capable of inducing a higher level of consciousness by directly interacting with the brain of pre-humans approaching it, the second (on the Moon) as an alarm signal designed to alert its creators that humanity had reached a sufficient technological level for space travel, and the third (near Jupiter in the movie but on a satellite of Saturn in the novel) as a gateway or portal to allow travel to other parts of the galaxy. It depicts Bowman traveling through some kind of
interstellar switching station which the book refers to as "Grand Central," in which travelers go into a central hub and then are routed to their individual destinations. The book also depicts a crucial utterance by Bowman when he enters the portal via the monolith; his last statement is "Oh my God—it's full of stars!" This statement is not shown in the movie, but becomes crucial in the film based on the sequel,
2010: The Year We Make Contact.
The book reveals that these aliens travel the cosmos assisting lesser species to take evolutionary steps.
Interpretations of 2001: A Space Odyssey - Wikipedia