Hi LDH.....No..Picaninni is really a very cute word....I have never heard it used in an offensive way ever. The source you quoted is totally incorrect.
The word Gin - referring to a female aborigine - is offensive. It never was originally but became so when it began being used derogatorial sense. ("She was as hopeless as a gin at a christening").
unclebruce will surely correct me here (as he should, because my spelling will be wrong) but our aborigines prefer to addressed as Murries or Koories. Depending on whether they were coastal or inland tribes.
Blackfellas and whitefellas are not derogatory words and can be used in conversation. Around here anyway.
Certainly many native women were raped by colonial settlers as has been the case world-wide since forever.
The Australian aborigine had (and still has) a culture 40,000 years old. And, as with any people that were invaded, were very badly treated. They resisted this intrusion and did try to keep their blood line pure.
PM me your email address and I'll forward a pic of my closest cousin......Wombat