Half-baked analysis, reads like an undergrad paper. By no means does the "it" in the movie clearly represent anything "passed on" by the parents' generation. Without being overly literal, the "curse" is passed around from kids to other kids, and while sometimes parents or adults are represented in the form of the invisible monsters, they are just as often other kids, known or unknown to the pursued. There is a long history of movies about youth, kids, teenagers isolated from their parents and adult society in general. This film is working from that material, not trying to make any particular point about youth inheriting a disaster-ridden world.
Or you could just be more "honest" and use some kind of flash or dissolve transition to show the clear passage of time. B-roll has always been the traditional cover up -- but even then I definitely avoid putting lines together that are in any way out of context from the original speech, or neglect some important point that was made in between.