This is a truly awesome resource and collection of history from Stephen Hackett. He went through all macOS (or Mac OS X, or OS X) releases and made a library of screenshots about the system.
These images came from the OS, running on actual hardware; I didn’t use virtual machines at any point. I ran up to 10.2 on an original Power Mac G4, while a Mirror Drive Doors G4 took care of 10.3, 10.4 and 10.5. I used a 2010 Mac mini for Snow Leopard and Lion, then a couple different 15-inch Retina MacBook Pros to round out the rest.
Check it out if you interested in Macs and UI design in general.