Primal

They call it Primal, the theoretical first language of the world that had both an oral and a written form.  A few scraps of script are thought to be the written form of the language, there is not enough of it to tease out much despite all the efforts by the Library and others over the decades. 
One great challenge is in the assumption itself that there was one universal language spoken by humanity in the past, that language development began in only one place and in only one time. This is not universally accepted. The premise is necessary for any trying to find Primal, the first language. A corollary to this premise is the theory that humanity lived in one place without dispersal until both spoken and written traditions developed.
Whether Primal is the original language as some insist, or just the oldest known written, the hunt is intense and the clues sparse.
Treasure hunters, farmers plowing fields, and workers digging wells, or roadways or foundations for buildings have all uncovered fired clay tablets, most about the size of a palm with various, obviously deliberate scratches on them. Over time most have made their way to the Library, to the half-dozen or so People who are the primary investigators. To date, the following is known:

1. It is some form of alphabetic script, the marks repeat in predictable ways in segments distinct from others.
2. It appears that the number of words available is quite high, there have been several thousand distinct 'words' identified, although not with known meanings for most of them.
3. It is believed that the users of Primal had a complex system of numbering, including the equivalent of zero.
4. Some scribes were much better than others, there are noticeable differences in style
5. The script seems quite persistent over time. When it has been determined that some tablets are older by generations than others, the script and common word blocks persist. If the language was evolving, it was also quite stable for much of the vocabulary.