Are there still languages that use native words for everyday usage?

The closest to a "pure" language or more accurately, a root language is Bushman. They are believed to be the oldest group of people. As people migrated out, they quickly lost the click sound and that's why it's not in any other languages. From there, languages spread out into the rest of Africa and eventually the world. The path of language evolution closely follows the map of the spread of mankind.

They remained isolated for most of humanities existence and their language therefore stayed in tact with little outside infiltration until modern times. They have however, adopted words for new concepts to which they were introduced.

This is the same for telephone etc. When a new concept is introduced into a language, it generally comes with a word. Telephones don't just drop out of the sky. That is why most modern technology has similar words in many languages. Today, the technology moves around the world so quickly that the words don't have much time to evolve before they enter many languages.

The most prominent example is the Basque language , which is called EUSKARA, and it has very few derivations from other languages The Basques live primarily in Spain, but in France as well close to the Spanish border, so that a few words are derived from Spanish and French

Another example is Gaelic, which is the language of Ireland, but there exist derivations from English, and only a minority speaks it, the majority speak English Hope this helps PS there are also numerous African dialects where there are few derivations from other languages

Why I cannot say one of the above languages? I am greek, and telephone is undeniably a Greek word hence is a native word to MY language.

Maybe there are tribal languages out there that haven't been influenced by others, but most languages contain at least some loan words.