Final answer:
Tim is talking about the physical growth in humans, which involves changes in body proportions from infancy to adulthood, as opposed to character development or film effects.
Step-by-step explanation:
When Tim in the movie says that people's proportions change as they grow, he is discussing the physical growth in humans. This means that as humans age from infancy to adulthood, their body shapes and structures change significantly. The ratio of limb length to body size, the size of the head in comparison to the rest of the body, and other aspects of physical appearance alter over the course of a person's life. Static characters, in contrast, may not show these changes and can serve as a constant against which dynamic characters and their growth can be measured.