We basically built towards a local maximum of what's physically possible for fossil-fuel powered sub-sonic aircraft; we also pushed into super-sonic, but the efficiency and noise pretty much preclude that for all but military and niche commercial operations.

However, there have been huge improvements in other areas, like efficiency and safety. Take a look at this fatal accident charts, and remember that aviation usage has been growing in the meantime, so rates per passenger and per passenger mile have been improving even more than this shows.

https://aviation-safety.net/graphics/infographics/Fatal-Acci...