When the humans discovered the Exarak Monument, they had unwittingly found records of an ancient race. Initially they were unable to decipher any word except one: Solinia (why?), a word written in the common trade tongue of the old world (how did they know that?) which every pre-cataclysm merchant knew. The humans could understand the word, but mistook it for a holy word when in actuality the old race just couldn't write it in any other language that would be understandable. Taking the word for themselves, they used it to name the world, in tribute to its 'divine properties' (why for the world though) and as a fitting name for the 'godlike' humans to use.
Overtime the humans were able to decipher other words from the monument and unlock some of the technology used by the ancient races which eventually became integrated into their society.