It takes no position for or against monogenesis or polygenesis.
From the en.wikipedia.org
Some scholars consider him a supporter of monogenesis, the theory that all languages have a common origin.
From the en.wikipedia.org
Supporters of monogenesis argued that all humans were descended from Adam and Eve and human slavery was a moral and spiritual outrage.
From the newscientist.com
Although Greenberg did not produce an explicit argument for monogenesis, all of his classification work was geared toward this end.
From the en.wikipedia.org
It does not presuppose monogenesis of these languages with unrecorded languages, such as those of the Paleolithic or hypothetical Neanderthal languages.
From the en.wikipedia.org
Linguistic monogenesis is the hypothesis that there was a single proto-language, sometimes called Proto-Human, from which all other vocal languages spoken by humans descend.
From the en.wikipedia.org
More examples
Asexual reproduction by the production and release of spores
The term Proto-Human language (also Proto-Sapiens, Proto-World) designates the hypothetical most recent common ancestor of all the world's languages.
(Monogenetic) Mendelian inheritance (or Mendelian genetics or Mendelism) is a set of primary tenets relating to the transmission of hereditary characteristics from parent organisms to their offspring; it underlies much of genetics. ...
The theory that mankind originated with a single ancestor or ancestral couple; The theory that all languages, or a particular set of languages, originated from a single source; The emergence from a single cause
(Monogenetic) A volcano built by a single eruption.
(Monogenetic) Resulting from one process of formation developing at one place and time.
The theory that, if two similar stories, words, or images appear in two different geographic regions or languages, they are actually related to each other rather than appearing independently. ...