Gerber has a long history, but it is not a single, frozen format.
For my first PCB, somewhere in the '90ies the DOS program I used had some 20+ different drivers for generating Gerber files. That was just yuck back then.
In the Gerber X2 format there is information in the gerber files for the layers and other stuff.
And then there is also Gerber X3 being worked on:
And apart from a file format for plotting, it can also be used as a reverse-engineering tool. KiCad’s Gerbview can export to a PCB, which recovers quite a lot of info for a PCB made in any other EDA program that can generate Gerbers.