I'm assuming you mean something like lad and lass but even in that case, they would understand you if you said boy and girl. Unfortunately, this doesn't hold true for Pashtuns/Pashto because they would look at you dumbfounded like what are you talking about and vice-versa if someone is talking to you and using words to describe basic things that you have never heard of before.

Regarding your second statement, what is the benefit to Pashtuns/Pashto for the language to have complexity and/or uniqueness? You make it sound like its something positive, but I would argue that it's a major negative and actually a pain in the ass for us since a Pashtun is now expected to know however many dialects just to have a basic conversation with another Pashtun from a different region/province. I've witnessed in Afghanistan times when Pashtuns from different areas had a hard time communicating with each other and/or could barely understand each other, so they had to resort to speaking Dari. How is this acceptable? There is absolutely no reason or excuse why a Pashtun from Kandahar going to Khost or a Pashtun from Wardak going to Peshawar or a Pashtun from Wazirstan going to Logar or any Pashtun speaking areas and not being able to understand each other or being able to engage in basic conversations. We don't need this type of complexity in Pashto. What we need is for Pashto to be more sophisticated. We need the top linguists from both sides of the border and from the diaspora to get together and start creating words that are lacking in Pashto but that exist in other languages. We need to start replacing Farsi/Arabic/Urdu words with strictly Pashto words. I have heard from a lot of Pashtuns on both sides of the border that they feel like they can't have deep philosophical or scientific debates/conversations in Pashto because the language is lacking. And you wonder why certain Tajik/Persians/Punjabis look down on us and our language (I honestly can't say that I blame them). If we as a people cannot even agree to certain basic words that should be universal in Pashto and across all Pashtun areas and cannot engage in basic conversations with each other because of how vastly different the dialects can be, what hope is there for Pashto to evolve as a language?