I mean, penicillin wasn't publicly available until 1941. So at that time, we barely had healthcare that was even worth paying for. I can understand why they deprioritized it.
I think people forget we've had truly modern healthcare for less than a century
Tl;dr - a large percentage of the list are birds from Hawaii that clearly didn't survive the introduction of cats. And several more are fresh water mussels probably lost to the zebra mussel invasion.