All recorded languages are likely descended from one of these
original languages:-
(1) The language of the first _Homo sapiens_ to arise in Central
Africa. This is "Proto-World".
(2) Perhaps very rarely in very favorable natural conditions in the
wild, a few children old enough to walk but not old enough to talk
much, get separated from adults and develop their own language and
manage to survive to adulthood and breed.
(3) In Europe a few words referring to local conditions and wildlife
etc might have got in from _Homo neanderthalensis_ languages.

But over time, languages evolve gradually away from each other and
change until remaining evidence of relatedness gets buried "under the
noise" of inevitable accidental resemblances such as Greek "theos" /
Nahuatl "teo:tl" = "god".