The Papuans belong to the Melanesian grouping among the Austronesians. The Micronesians and the Polynesians are the other two members of the Austronesians. The Malayo-Austronesian connection is strong based on ancestral migrations thousands of years ago via land and sea. During the Pleistocene period the limits of land were extensive that many of the present islands were connected by land bridges.
In fact we are now grouped as part of the Austronesian in a broader concept.
There are many aboriginal tribes in Papua New Guinea. In the highlands there are the Dani, Sibil and others. In the lowlands where sago palms grow into sago forest, the Asmat is among the tribes that subsist upon the palms.
Cannibalism was a practice before. Warring parties are still common.
Margaret Mead, a famous American anthropologist spent many years studying the Papuans. "Growing up in Papua New Guinea" is one of her books.