I don't believe that any one of us has all the answers but we can piece together much of what we need from different sources.
IMO, there are only four monotheisms: Christianity, Islam, Communism, and Western Grand Narrative (Secularism, Liberalism, Manifest Destiny, Racism, American Individualism, etc). Advaita, Buddh"ism", Chinese traditions, and so on are 'experiential' entities and not 'belief' and ideological entities in the fashion of monotheism. There are authors (namely the Ghent group) which have systematically explored the differences between orthopraxic heathen traditions and the orthodox believer "religions". Centralization as seen with China, Mauryas, are not same as the religions required to prop up empires.
Under colonial conditions, a monotheist veneer can be imparted to these traditions; thus we can now speak of Sikh monotheism, Brahmo Samaj, and Buddhism as protest against "brahmanism". As said by Shri Ram Swarup, the British ruled through Indology. But the Gurus are not prophets militating against the unbelief of idolators; this is a simply "point" reinterpretation by Indology and imparted to susceptible elements in the community with colonial intent. The point is that the lineage of "prophetic gurus" is revisionist history and reinterpretation of an authentic tradition of gurus.
Judaism is remarkable in that, unlike Christianity and Islam, there is not just one prophet, nor is there an abrogation of previous versions of the revelation. In fact, in the first century "kingdom", there was a veritable proliferation of prophets, all predicting end of the persecuting Empire. "Last Prophet" psyops was instituted only with Christianity, quietening the revolutionary chatterati.
The Sikh guru lineage ended with the martyred sons of Guru Gobindji. Upon this edifice was instituted the colonial indology's claims of the gurus abolishing idolatry and the like. Apparently the Gurus were all consummate anti-Hindus and their anti-empire efforts were all incidental posturing. To us, the revisionist history is obvious, but the multiplicity of Judaic prophets all similarly have Bel and El inscribed within their names. OT Genesis' geopolitical landscape (Shem, Ham, Japeth) is an exact match for the Alexandrian successor empires (Seleucid, Ptolemaic, and mainland). No other period of history has a correspondence even in broad outline.
pan-Europe concept only came with Christianity. Why were they not able to evolve a Bharatiya or Han-type identity with an intact "polytheism"?
And then we have the interesting statements from the Ghent group localizing Normative Ethics to the 'Ethica Nichomachea' of Aristotle (the article has been apparently deleted from Sulekha). Aristotle is Alexander's "teacher".
Monotheism has an inbuilt mechanism to escape the scrutiny of the victim. The victim's gaze is directed elsewhere, eg the native ancestor, while imperial action as such remains unexamined. the victim will even celebrate his capitulation as revolution and his degradation as self-assertion. Under these circumstances, it is incredulous to expect some nondescript tribe in Palestina to come up with Monotheism.