Falling safely is a skill many actors learn and the practice is often called a “pratfall”. It is a skill widely used in comedy and action, and when done well is convincing both on stage and screen.
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Beyond that, there are a huge number of optical illusions that are used by actors and cinematographers all the time. Sound effects also play a part in encouraging our brains to interpret what we see on the screen in a certain way. Often, what very much appears to be happening isn’t actually what’s happening.
For example, trained actors can make it seem like one is slamming the face of the other into some surface, when what’s actually happening is the face is just getting very close without hitting the surface. The camera angle, lens, focus, and lighting can all play a part. A bit of fake blood and some sound effects and the illusion can be very powerful. These days things might be enhanced digitally as well.
And I should add that these days, it’s not certain that anything that appears to be a single shot is a single shot. Nor is it certain that anything that appears to be a hard wall or floor is what it appears to be. Even amateurs can make convincing photorealistic environments and surfaces in software like Blender and Unreal Engine. A well lit green or blue colored mat could easily be digitally replaced with a hard concrete floor or cinder block wall.