So Latin spread pretty well across Europe, being the basis of almost every language there, but how come it didn’t take as strong a hold in the Middle East? It’s not as if the Romans were never there, and they lingered there far longer than they did in Europe. Was it just a matter of a stronger preexisting culture, or did the Arabs have something to do with it? What happened here?
If we replace Latin with Greek, I’d say that the European areas were either just never conquered for long enough periods by people with different languages, or the conquerors weren’t enough (or not brutal enough) to enforce the spread of their own language; e.g. the Franks conquered Vulgar Latin-speaking France, but they adopted the Latin-based language instead of making everyone else speak a Germanic language. Closely related to that is that Europe was almost fully christianized, which is heavily based on the Latin and Greek languages, while the middle east was almost fully (muslimized? islamized? there’s got to be a word for that).
Maybe a third, by population. Germanic and slavic languages are a thing, they aren’t based on Latin even if they use many Latin loan words.
You’re forgetting an important aspect: It was cool to be Roman back then. The people who conquered the Western Empire were people who wanted to be part of Roman citizens but were refused by the xenophobia of the late Western Empire (not to mention the whole christianization thing), and would essentially larp as Roman for a bit, so it’s not like they were in a rush to assert ethnic dominance. “Barbarian” peoples conquering centers of civilization and assimilating into them rather than vice versa is a pretty common thing in history, see: the Mongols. This as opposed to early Muslim Arabs, who rode their own religion and culture to regional dominance and would have them spread across their conquered territories instead.
“Islamized” is the word.