As another post has said, a great many of the world’s languages are related. Hindi and German (and many languages in-between) are part of Indo-European, which is a family that people pretty confidently think came from just one language thousands of years ago. A lot has changed, but some basics of how the language works, and even some words have stayed similar. For example, the Hindi word for fire is “Agni”, which is related to the English word “Ignite”. That’s not coincidence – it’s because thousands of years ago, they were one language that changed as people moved apart. Remember, if you read English that’s only 600 years old, it’s very hard to understand. Imagine how big that difference would get over many thousands of years.
Now, there are many languages that *aren’t* part of that big family. But many languages are indeed part of a different big family like that (for example, Afro-Asiatic is a big family that encompasses languages like Hausa, spoken in Nigeria, to Hebrew).
If you did know that, and you meant it on a more fundamental level, we don’t actually know. But it’s easy to imagine that everyone needs a word for things like “yes” or “no” and to describe things like colours. The actual words for those concepts might and do sound very different in languages with no relation to each other, but they will exist because they’re words that people almost always need when interacting with each other in a society.
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