Once again, we really don't know for fact. See if this makes since to you. One day an Aboriginal person was shaping a smaller, lighter slightly more bend throwstick than he normally used. No one really knows. What we do know is they made it and passed the technique down through generations of time and we have it today, thankfully.
Life is no fun without playtime.
Returning boomerangs were used as toys and for sport. Of course the Aborigines used what few tools they had for all manner of tasks. They would use Kylies and boomerangs to dig up roots to eat. They would use them as cooking tools. They would also use them to rub or clack together to make music.