Not sure if that's a real question, how you would have copied files 5+ years ago between phones? Support for USB host mode was introduced with Android 4, released in 2011, but would have required the use of an OTG cable so that would likely not have been an option.
Popular Android file managers at the time had file transfer capabilities so that was probably the quickest. The advantage is that they used normal file transfer protocols which were available everywhere so the other party didn't require any special support.
However a decade ago all phones had SD cards, because their internal memory storage was so small so you needed them should you wish to use the camera beyond any trivial amount. So just copying that way would probably have been what most people did.
Popular Android file managers at the time had file transfer capabilities so that was probably the quickest. The advantage is that they used normal file transfer protocols which were available everywhere so the other party didn't require any special support.
However a decade ago all phones had SD cards, because their internal memory storage was so small so you needed them should you wish to use the camera beyond any trivial amount. So just copying that way would probably have been what most people did.