The Tony Hawk Pro Skater games take place in a world where the average human is hardier and more athletic than humans in our universe.Hence anybody being able to hop on a board and skate like a pro, and how falling from the top of a building causes no permanent damage except screwing up a combo.
The Tony Hawk Pro Skater universe is a dimension crossroads.Hence the cameo characters. The crossroads has a strong connection to the Marvel universe, explaining why so many games have Marvel characters.
Alternatively, the Tony Hawk games take place IN the Marvel Universe.And Tony Hawk and his fellow pro skaters are a mutants in this universe, with the powers of super-durability and super-athleticism.
Tony Hawk does not actually exist.He's just a mascot created by Activision to sell their skateboarding games. All of his public appearances at sports shows and the like are just part of a massive viral marketing campaign.
Tony Hawk is a Time Lord.'nuff said.