Barry: Makes you wonder is Englishman or Australian man or Scotsman is also just as offensive
That is not an accurate comparison. Comparable terms would be: Englandman, Scotlandman and Australiaman.
And to make it even more comparable, the Englandman, etc, would have to have been used to build railroads in China. The Englandman and the Scotlandman would have been the ones to get blown up with dynamite instead of the Chinese.
Yes, "Chinaman" is an offensive term. It is a stereotypical term that removes the Chinese people's individuality and designates them as a slave class for the Englandman and the Scotlandman and the Australiaman.