Why words like 'okay' and 'taxi' are universally understood across the world but survival related ones like 'help', 'water', 'food' remained nation specific?
Because you have the important words before you come into contact with another culture. You only borrow words you lack
The survival related ones came to have names because they are integral to survival. People needed to address them, and so they did. With local isolation or dialects or divergence.
Okay, taxi, cola became popular and expanded their reach. They did not arise in individual and dispersed areas, they traveled.
In a similar vein, this concept is useful to try and figure out where certain technologies were invented independently and where they spread through trade.
Survival words, as you would expect, exist in every language and have existed in every language for a long long time, likely since their inception. It is rare for a word that has existed for a long time to be removed from the lexicon, especially for another languages word entirely (though it does happen).
A "taxi" as a concept is a relatively recent invention, meaning a word for it did not exist in any language before then. And by the time it was invented, the world was far more interconnected than it had once been. As such, many languages, instead of create a whole new word for this new concept, borrowed the word from the place that created it, which in this case spoke English.
A similar case exists for the word "okay". I don't know if it's just a legend or a true story, but supposedly it was a way that a former president use to give his approval on documents, stamping it with the "OK", which stood for Ol' Korral, his ranch. Regardless, "OK" (sometimes lengthened to "okay") became ubiquitous and synonymous in the US with approval or acceptance of something. Again, due to the connectiveness of the world that is only a recent development, relatively speaking, the new shorthand phrasing spread to languages where there wasn't already an equivalent. It is a handy shorthand way to express a sentiment of approval, so many we happen to adopt it wholesale.
There are similar words, phrases, and abbreviations we use in English as well, sometimes with some anglicized spelling or pronunciation, sometime just a straight carbon copy. Names of foods like "burrito" (Spanish), "beef" (French), "hors d'oeuvres" (French), "sushi" (Japanese), or "cookie" (Dutch). Concepts like schadenfreude (German), a metropolis (Greek), or avatar (Sanskrit). Phrases like "R.S.V.P." (i.e. "répondez s'il vous plaît", French), modus operandi (aka, "m.o.", Latin), Et Cetera (aka "etc.", Latin), and Faux Pas (French). The more connected the world is, the more language mixing we will have, especially as new concepts arise and are borrowed by others.
"Why are words" is a question.
"Why words are" is an explanation.
Yeah it's only a creeping error that's making English harder and search engines worse. Fuck me sideways for politely highlighting the difference in a thread about language.
Don't worry, it's a pet peeve of mine as well, shallow and pedantic or not.
It's easy to just use sign language for those.
Waving your arms frantically, and miming a drink or eating food are pretty universally understood.
It's why every European language just slaps an accent mark on the word "airplane" because we invented the tech and created the name, so they just adapted it to fit the pronunciation of the phonetics in their own vocabulary.
𝕱𝖑𝖚𝖌𝖟𝖊𝖚𝖌 would like a word
Clément Ader did it in 1890