The evolution of cameras has been less of technology, more of democratic access. The template for 35mm cameras has been around for almost a century - cinema film used in hand held cameras with variable aperture and shutter speed and high quality lenses. What's changed is access to the type. An early Leica would have been a substantial investment for a privileged middle class person, for an ordinary guy buying one would be unthinkable.
By the 1960s SLR cameras were beginning to come into enthusiast budgets, and the Canon A-Series of the late 70s democratised them further with plastic, battery powered, mass produced models. This has reached its natural conclusion today, with artisan made 35mm cameras costing £10k with a lens, offering results virtually indistinguishable from a camera costing the price of two or three rolls of film.