The Rabbinic tradition is that the original language before Babel was Hebrew and after my studies of the language in college, I can totally buy that.
"The Complete Dictionary of Hebrew Language" has about 35,000 words in total. I bet that over a half of that aren't used, and would sound completely new to anyone except Hebrew linguists.
Hebrew is a "tabular" language that can be represented as a (sparsely populated) table with the roots as rows and "morphemes" (construction patterns) as columns. If a word exists, it will be in its proper place at an appropriate row and column.
Here's an example of a construction pattern for the category of "tools":
maXXeXa
The X denotes a place to put the root letters. Most of the roots are composed of three letters, and so there are three places.
When you combine it with the root S.R.T which has a meaning of "ribbon" (and also, film), you get "maSReTa" — "a tool for making films" (video camera).
If you combine it with the root Ts.L.M which has a meaning of "image", you get "maTsLeMa" — "a tool for making images" (still camera).
Even if you never heard the word "maVReGa" but are able to separate it into the morpheme of "tools" and the root V.R.G (which has a meaning of clock-wise motion), you can use that to understand the word as "a tool for making clock-wise motion" — a screwdriver.
The other challenge with Arabic is that the script is considerably more complicated since most letters have distinct initial, medial and final forms whereas Hebrew only has special final forms for three letters. That said, I know almost no Arabic so I can’t speak with much authority on its learnability.
The lack of vowels also trips up non-native speakers/readers.