These cards are all around a hundred years old. The top three are unused and in surprisingly pristine condition.
This is number 38 from the series published by Phillipe & Sons aka Funk & Sons. The caption says "Borneo children" and the photo was not necessarily taken in North Borneo. The enclosure kept out crocodiles which posed a real danger by the river and even on the coast.
That lone tall tree reminds me of somewhere on the east coast.
This is number 50 from the series by Funk & Sons and almost certainly taken somewhere on the west coast.
It is difficult to know whether this was taken in North Borneo but the houses of coastal folk should be fairly similar. It was card number 1980 by C Piens of Kowloon, Hong Kong but printed in Germany where quality was the best.
This is card number 58 by Funk & Sons which was taken by Ha Buey Hon of Kuching, Sarawak. It depicted the native Dyak women of Sarawak. There would have been very few Dyaks in North Borneo.