if you are going to use Iranian sources to support your argument, then you need to follow the rule of consistency, not pick and choose sources tat fits your purpose.
In Iranian - Avesta, the term Arya - refer to ethnicity
airyō.šayanəm "land inhabited by Iranians
airyāfi; daiŋˊhāvō "Iranian lands, peoples
Inscription of Darius the Great
(8-15.) I am Darius the Great King, King of Kings, King of countries containing all kinds of men, King in this great earth far and wide, son of Hystaspes, an Achaemenian, a Persian, son of a Persian, an Aryan, having Aryan lineage