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Should languages ​​spoken by two similar races have the same protolanguage, or can they be not related by protolanguage? I guess they should be similar for example in phonetics or in some other features (grammar?). But should they be created from one protolanguage?

the same question on worldbuilding.SE

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I guess this is up to you as the world builder.

Note that there is no known connection between language and race, all human beings no matter of of skin colour, hair, or other characteristics used to define "race" can learn any human language as their first language. Large language families like Afro-Asiatic, Austronesian, or Indogermanic cross the boundaries of continents and races.

So again, it is up to you, depending on the in-world history, geography, and your personal preferences (some conlang inventors like modelling diachronics, other prefer to invent unrelated languages).

Note also that there is a phenomenon called sprachbund: genetically unrelated languages develop common features due to close contact. There is a famous sprachbund on the Balkan, there is Standard Avarage European, there are the Pacific Northwest languages forming a sprachbund with some interesting and maybe insipiring common features.

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