It's important to understand what the monolith is in movie. It is a device left behind by an advanced race of aliens who want to encourage "Mind" or intelligence. They do this by giving evolution a kick in the direction that suits that goal. For mankind, that direction was enhanced aggression and tool use. After we started to grow, we were monitored by the monolith on the moon. When it was discovered, it led us to Jupiter. When we got there, we proved that our development was worthy of the stars. So one of us was selected. Bowman. He was brought into the monolith via the 'Star Gate' which was the lights in the tunnel. Then, when Dave reached the inside, he was pushed through his life in a quantum sense. When he experienced a moment, he became that moment. Finally, at his death he was given a cosmic understanding and reborn as the 'Star Child.' The secondary plot involved human politics and lies corrupting a pure AI in HAL9000. Driven mad by his contradictory instructions, he terminates the crew with the intent of completing the mission on his own. Did that help?