Languages always undergo change, and one of the reasons for change is the adoption of more suitable terms to refer to people in order to respect their sensitivities and avoid insulting them. For example, when I was young, people used to refer to Red Indians, but nowadays that is not regarded as appropriate, and we talk about Native Americans instead.
In Taiwan, it is exactly the same. When I was here thirty years ago, the aboriginal tribes were referred to as 山地人 shān dì rén ('mountain people'). But the problem with this is that these people never used to live in the mountains until the arrival of the Han Chinese who chased them out of the plains, so calling them 'mountain people' is rather insulting. As a result, they are now referred to as 原住民 yuán zhù mín ('original folk'), and this is far better.
Of interest to people in Brunei, Malaysia and Indonesia is that the language they speak is related to Malay. In fact, it is generally believed that Taiwan is the origin of the Austronesian languages. You might say that Malay comes from Taiwan.
One of the ways to demonstrate this is to consider diversity. If you look at English, you will find that there are lots of different varieties in England, and often one town (such as Newcastle) has a completely different accent from the neighbouring town (Sunderland). In contrast, in Australia there is much less regional diversity, so there is not much difference in the speech of those from Perth, Sydney and Melbourne. In just the same way, there is considerable diversity between the Aboriginal languages in Taiwan, though they are still all Austronesian. In contrst, there is less diversity between the different varieties of Malay.