No, eariler versions of Mac OS were based on Guess what..... Eariler Versions of mac OS. So each one improved on the other and it was a very good OS.
EX. OS 7 was built from os 6. OS 8 was made from OS 7 and so on.
Jobbs saw the oppuritunity to blow microsoft out of the water with an OS based on UNIX. and he succeded. the so called LONGHORN project of microsoft is to try and match the features of OS X. So the windows vs mac war continues.