For example the Tibetan Government in Exile as well as New Qing Historians downplays the Chinese-ness of the Qing. The current PRC government does not equate China with Han. Why is Chinese automatically equated with Han when both the Qing and PRC emphatically equated Chinese with ALL the peoples of Daicing Gurun/Zhonguo? Why does the word Chinese imply Han-ness in English more than the world Zhongguoren imply Han-ness in China itself? Why is the "Chinese" moniker more ethnically/racially? rigid in Western Historiography compared to Historiography within China where the concept of "Chinese-ness" was much more encompassing in the last 300 years? Why does the Chinese identity have to be fixed and immobile? Is there a barrier to accepting that "ethnic groups" in the PRC can have multiple identities (i.e. a person can be both Manchu and Zhongguoren etc. and not be contradictory) in Western Historiography?
First of all I would say what the PRC government says and what actually is the case are completely different, particularly as they like to utilise race and minzu for political purposes.
Historically, Han chauvinism has been and continues to be core to the social and political history of China. Since the Han people make up the majority of the population, it is of course natural that the fundamental association of China and the Han people by laymen remain strong. This does not, however, mean that scholarly interpretations of China equates to Han.
Therefore, I am quite confused with regards to your other questions. In no serious scholarship do scholars outright equate China as Han. Could you be more specific as to what you mean by Chinese implying Han-ness in English more so than in China? How is the Chinese moniker more rigid in Western Historiography? Can you give me some examples?
Sources to consider:
Frank Dikotter, Discourse of Race in China
Thomas Mullaney, Coming to Terms with the Nation: Ethnic Classification in Modern China (California, 2011)
Gardner Bovingdon, The Uyghurs: Strangers in Their Own Land (Columbia, 2010)
Melvyn C. Goldstein, Ben Jiao, Tanzen Lhundrup, On the Cultural Revolution in Tibet: the Nyemo Incident of 1969 (UCalifornia Press, 2009)