When the early hominids encounter the unfamiliar monolith, they jump around. The camera approaches the monolith as the hominids explore it. As the camera closes in, the monolith acts as a marker to emphasize the changes in distance.
As the shot gets closer, it gets harder to see the various hominids. Several go behind rocks or out of the frame. In the original shot, these obstacles wouldn’t affect our view of the hominids.
As the hominids learn more- it won’t attack or run from them, it won’t burn their hands- their movement stills until they resemble the monolith. They form a fixed black clump.
This sequence supports the common idea that unfamiliar tech leads to new ideas. In this case, the new ideas result from the emulation of new technology. This challenges the perception of such ideas as “new.” By exploring this challenge in its opening scenes, the film prepares viewers for Hal’s emulation of humans and discourages a reading of the humanized robot as “new.”