What would happen if every person on Earth suddenly gained the ability to fly, and how would society adapt to this new reality?
Your question, as it is indeed interesting is also a hypothetical. Because of that, we can only imagine what would happen and how it would affect on society.
But here are some things that would most likely happen.

- Transportation: The transportation industry would change dramatically, as air travel and air traffic control systems would need to be reconfigured to accommodate widespread flight. Many forms of ground-based transportation such as cars, trains, and buses would likely become obsolete.

- Architecture: Buildings and urban planning would have to be redesigned to accommodate flight. Elevators and stairs would become less necessary, and cities could become more vertically oriented.

- Workforce: Some jobs that are currently limited by the need for workers to be in specific locations, such as construction and maintenance, could be performed more easily and efficiently by workers who can fly to the work site.

- Military: The military would likely have to adopt new tactics and technologies to respond to the possibility of air assaults and to defend against airborne threats.

- Safety: New safety regulations and infrastructure would have to be put in place to ensure the safe use of flight. This could include air traffic control systems, air traffic lanes, and emergency response protocols.

In general, society would have to adapt to the new reality of widespread flight by rethinking many aspects of daily life and by developing new technologies and systems to accommodate this new capability. It would likely be a time of great change and uncertainty, but also of tremendous possibility and opportunity.

The sudden widespread ability to fly would likely also have an impact on popular culture, fashion, and entertainment. The sale of superhero costumes and other flying-themed merchandise could increase, as people embrace the new reality and explore their newfound abilities through play and self-expression. This could lead to a boom in creativity and innovation, as people imagine new uses for flight and incorporate it into their art, music, and other forms of entertainment.