I parsed it as saying
"in the original trilogy the only trained force-sensitive people we hear of are 3 human male and Yoda."
STOP, now a related thought about why one of them is unlikely to reproduce due to the limited female characters in the movie. "On top of that we have a brother and a sister."
But I can see how your reading of it would make sense, since it removes the potential count error I read it as having.