But upon the initial release in 08, Android had already been in development for some 5 years.

Maybe, but among other things, it was also running Java code on a pure interpreter :)

I don't have any personal experience of either the ZTE Open or G1's performance, but an ancient Android phone shouldn't be a hard target to beat.

Missing the key detail that huge parts of the Android stack, even then, were not interpreted Java. (Skia, for example)