A human could swallow a loose tooth if the tooth comes completely loose and you either purposely swallow it or accidentally swallow the loose tooth in your sleep.
However it's unlikely that you would swallow the loose tooth in your sleep because it would likely wake you up in time before the tooth made it's way into your throat and your tongue would likely keep the tooth away from your throat.
It's unlikely that you would actually choke on the loose tooth if you did swallow it though because the tooth is small enough that it shouldn't pose a choking hazard.
My son lost his tooth in his sleep when he was 8 years old and he woke up and removed the loose tooth after it came completely loose and he didn't swallow it or choke on it.