Yes there were Iranians. Eranshahr / Eran was the official name of the country under the Sassanid dynasty.
en.wikipedia.org
I understand the zionist regime is bent on denying Iranian nationhood and is actively engaged in attempting to provoke territorial and societal balkanization of Iran (akin to what could previously be witnessed in Syria, Iraq, Libya, Somalia, Sudan and Yemen) along "ethno"-linguistic lines, however truth is that the concept of Iranianhood stretches back several millennia, like it or not. Iran is one of the eldest nations and states in the world.
First of all, the historicity of the text very much stands to debate (see source below).
Secondly, as I explained earlier in this thread, what's more interesting from the contemporary perspective is how Jewish authorities as well as zionists go about interpreting it.
Various qualified rabbis do not appear to share your above expressed speculation. Here's an example of what one cleric appears to assume the ethnicity of the victims might have been according to the authors of the Book of Esther:
https://www.jewishnews.co.uk/the-megillah-says-what-we-killed-75000-persians-on-purim/
View attachment 945753
This said, Iranian secular nationalists hold the belief that ancient Iranian empires treated conquered nations well. In that sense they would rather tend not to stay entirely indifferent to news of mass killings, be they focused on ethnically non-Iranian subjects of the empire. At the very least would the public in question show interest in learning more about the purported event.
Not to mention that from the perspective of the Book of Esther, chances are either way that at least a non-negligible portion of those 75000 would be deemed to have been native Iranian people.
I'll transmit the message to Iranian nationalists and secularists whom zionists have been recruiting in their confrontation against the Islamic Republic. That 75000 of the Sassanid empire's inhabitants (a large number for that time, equivalent to several hundreds of thousands in the present day) deserved to be put to death for plotting to harm Jews under concocted pretexts. This would point to an extremely elaborate plot and a high degree of organization, involving large numbers of people (from Africa all the way to India?) against a much smaller community.
Surely you'd have been able to substantiate this accusation with some evidence if it were true.
I'd advise against twisting my words though: such an endeavor might end up making the content of the Book of Esther appear less than credible in the eyes of readers, seeing how you likened the mindset of Judeophobes depicted therein with my purely scientific analysis, to which one would be hard pressed to ascribe any form of racialist prejudice.
On the contrary, this thread does have a very specific and important point which I duly elaborated upon in the opening post: the story of Mahoza, the Book of Esther as well as several reports of persecutions of Jews at the hands of Iranians in subsequent centuries go a long way debunking one particular zionist narrative exclusively aimed at Iranian audiences. Namely the notion that ties between Iranians and Jews on the one hand and relations between Iranians and Arabs on the other hand could be radically contrasted with each other, with the former being portrayed as invariably harmonious and the latter as tremendously conflictual.
This narrative in turn is used by exiled Iranians oppositionists as well as by in-house liberals - both of whom are being backed in various ways by NATO and the zionist regime, to take aim at the Islamic Republic's policy of Resistance against zionism, by construing "the Arab" per se as a historic foe and "the Jew" per se as a historic ally. That this typically romanticized discourse has had an impact on the representations of Iranians opposed to the Islamic Republic can readily be seen through examples on this very website.