Did the aboriginal people keep their language the same?

Depends where they are. Aboriginal (Indigenous) Australians living in urban areas generally speak English, some with a heavy accent and some with almost none; those working on outback stations frequently speak a mixture of their local (birth) dialect and English, and remote communities might speak a variety of languages (sometimes just called "language" rather than labelled with the title of the language). This makes remote education and communication with health and other English speaking workers difficult; the onus has always been on the indigenous people to learn English, which, if it was the other way round wouldn't be countenanced for a moment. The result is, among other health and wellbeing issues, many indigenous children simply give up on school because they don't understand the language they're being taught in and their teachers haven't a clue what they're trying to say. Some children growing up on remote stations learn from staff and management; it also works both ways: one of my sons spent several years on Northern Territory cattle stations as a teenager and though from an Irish-Australian family has never quite lost the accent.