Linguistics; history of language
One trick to linguistics is to learn to not be elitist about linguistics. If you look at language with a sense of equality, and not as an institution on high that's Cambridge-approved or whatever, it morphs and evolves a *lot*, and every culture has a stereotype of each other.
Linguistics; history of language
Polari is a linguistic deviation. So is Ebonics -- whether the original term referring to the language of all descendants of Black African slaves, or the modern term of Vernacular English. It's language, it evolves and changes and combines into something new & interesting.
There are people that would frown on that idea. There's also people in Singapore who look down on Singlish. Or Spanglish. But that's a linguistic deviation. It's valid. It's legit.
Linguistics; history of language
And in languages, lingual drift is what you get with population drift. That's a big reason why there were so many different languages that made it hard for people to communicate. They split up.
You get populations splitting apart, coming back to meet each other, and then coming up with whole new words that were really your old words but different now. (Example: "shirt" and "skirt" used to just mean "skirt", which is to say shirt. English dropped the k to h)
Linguistics; history of language
(But if you really know Old Germanic, you're gonna get a lot of it.
If you know Old Germanic AND, say, old Latin, and say... Middle French, you're pretty solid on pretty much getting the gist of Middle English)
Linguistics; history of language
Specifically: Old English, back when English was much more a Germanic language is is virtually unintelligible to anyone today without training.