RebRy – I say “closest” because there are innovations. They didn’t have a word for ‘refrigerator’ back then because it didn’t exist. Nonetheless, even the Mishna – which I assume we can all agree is lashon hakodesh – at times takes words from Greek, Roman, and Arabic. Often, modern Hebrew takes from Aramaic to speak of new innovations. One example that comes to mind is “?????” – “ice cream” is the word “frost” in Aramaic, that is used in Onkelus to describe the ‘manna’ (??) in ???? ?’ ??.
Chazal say the sole reason that Hebrew is considered Kadosh is because it has no words that are inherently vulgar. Modern day Hebrew dialect has to borrow from Arabic, Yiddish, and English to create dirty words. The language is still holy, because the words used by Israelis are just part of the evolving colloquial dialect (read: slang), not part of the actual (non-slang) language.
The laws of dikduk, grammar, and conjugation are almost entirely similar. This is why an “Ivrit” speaking individual has a very easy time reading Mishna and Psukim.
There is no question that Yiddish is not a holy language. Aramaic is unique b/c the malachim don’t understand it, but it’s not holy. No language other than Hebrew is holy.