Linguists don’t divide languages into “oral” and “written” languages; nothing special changes about a language once a writing system is developed or used. As children, we learn the sounds and grammar of language through hearing it spoken to us and around us (or signed, for people who grow up with access to a sign language). We have a fairly mature grasp of the structure of our first language or languages by the time we start learning to read and write, which has to be done through explicit instruction. Language exists independently of writing; writing is simply a technology and a practice that some societies use and others do not. It is a technology that is relatively new to this continent, where, at the time of colonisation, hundreds of incredibly diverse languages were spoken but not written (although there were and still are other types of complex visual semiotic systems).