Re: Why is Urdu considered an Aryan language?
This is not a good argument. Persian script is distinctly Arabic. Does it make Persian a Semitic language? English script is distinctly Latin. Does it make it a Romance language?
Script for Urdu was chosen after Muslims arrived speaking Persian language. But local people were already speaking various “prakrits” before the advent of Muslims and Persians.
Urdu is just one such prakrit which was spoken around Dehli.
Oh, I get it. I understand where you are coming from. 
sigh.
I think you are assuming that I am trying to say that Urdu is the language spoken by Indus Valley civilization. This is both true and false.
The language that Indus Valley people spoke was the mother language of Urdu. But not just Urdu. It was the mother language of Punjabi, Sindhi, Siraiki and Gujrati as well.
No language which is lingua franca of millions of local people could emerge by someone artificially amalgamating it with other languages of his choice.
Fact is that people were already speaking a language (obviously) when Persian/Turkish speaking Mughals arrived. Since Persian was the language of the courts therefore Persian words were included in the local language in huge numbers. Just like French words were added in great number after Norman-French invasion.
This local language was later called ‘Urdu’. But just because it was named ‘Urdu’ after Mughals arrived, does not mean that the language started only after it was named as such.
Urdu existed as a language before Muslims came, even though it was not called Urdu. This is the same as other languages like Punjabi and Sindhi. They also existed long before people started calling them Punjabi and Sindhi.
All these languages are thousands of years old languages.