To my ear, if the sex of the child is unknown, it would be better to say “the otter dragged it underwater.” “Them” seems bizarre to my language sense.
I know what you mean but “it” is reserved for animals and objects.
However...If I were into pronouns “it/the” would be mine.
:)
The ‘singular they’ has been in common use in English for hundreds of years:
https://en.wikipedia.org/wiki/Singular_they
Or, “the child was dragged under water by the otter.”
I would go so far as to say otterwordly.
“To my ear, if the sex of the child is unknown, it would be better to say “the otter dragged it underwater.” “
I would never in a million years use the inanimate pronoun “it” to refer to a human being. That’s what abortionists do.