A discussion on the origin of language? You've caught my interest.
Yes, they're all Indo-European languages. English and Pashto are related in pretty much the exact same way that Arabic and Somali are; genealogically, they were once one language which broke up into dialects, which became different enough to become languages, then each one broke up into dialects again which over time became their own languages, the cycle continues.
The point where a dialect becomes a language is hard to define. Both of us being from the Gulf, I think we share the sentiment that Moroccans are really hard to understand just because their dialect has diverged so much from the kind of Arabic spoken in the Peninsula.
The last time English and Pashto were the same language were the same language was circa 2500 BC (the language being called Proto-Indo-European, or PIE), so about 4500 years ago. Their similarities are rather difficult to see, that is until you look much closer. Much, much closer.
I think the easiest example is the numbers "two" and "three". In Pashto they're دوه and دري respectively. Keep in mind that in Old English, the word for two was "twa". Pretty similar in pronunciation, right? Even more similar is the Latin word for two, "duo".
That's just an easy example; there's way more and you need to peel back a lot of layers to find them (like an onion)...
Lots of videos about it but here's one I like.