Are they, like, two totally separate languages?
You got it on the first guess.
While they are both Semitic Languages (in the Afro-Asiatic family) they both evolved from different precursors. Amharic’s being some form of proto South Semitic and Arabic from a proto Northern one.
In fact the Arabic/Hebrew split is a more recent one than either’s with Amharic (or any other South Semitic Lang). However such language trees are academic and don’t take into account recent influences (loan words, etc).
Here’s the complete and unnecessarily-detailed-for-your-question breakdown of the relationship of the two languages.
That chart is quite dated as it still ties all non-Semitic languages, in the Afro-Asiatic family, as “Hamitic” (under quotes). Linguists stopped using that false-differentiation/grouping in the 1950’s.
Sorry, I just did a quick search. Didn’t look into it much.
No need to apologize. It’s still cool (If a bit old).
Here’s the tree for the Afro-Asiatic family from the website Ethnologue, which has information about all the world’s languages:
Good point. To make an analogy, English is a West Germanic language. One of the reasons that it is now so different from modern German and Dutch is that it was influenced heavily by Norse and French due to conquest and contact while German and Dutch were not impacted as much.
In fact, why isn’t English considered a creole? First between the West Germanic Angles and Saxons and the North Germanic Jutes and then between that an Norman French (in turn a Norse influenced derivative of Latin).
Indeed, it’s a fine line. Some linguists do consider it a creole. John McWhorter wrote a technical but very readable scholarly article on how English grammar probably changed (simplified, mainly) not during any of the periods you mentioned*, but rather in the 700s (I think it was), when many Danish men sailed over and married English women (mainly in East Anglia, or was it Yorkshire?). They spoke a simplified English to each other, and that’s what their children learned as their first language.
(The only major Germanic language that has been yet more creolized is Afrikaans).