I feel everyone needs a reminder about how North America also includes Mexico, Central America (Belize and Guatemala to Panama), and the Caribbean are all part of North America.
Since the game identifies animals on continent, with Australia, New Zealand, and the Pacific Islands as “Oceania”, Central America being under North America is correct.
Ecologically speaking, Mexico is the transition zone from Nearctic to the Neotropics. It’s one of the reasons it’s considering a mega biodiverse nation. South Florida is considered part of the Neotropics (and having been to Miami, along with western Mexico, and Costa Rica, it tracks).
Central America is both a melting pot and a region with many iconic species found nowhere else on Earth. The Caribbean has many endemics, something islands do very well.
Not every animal found in Central America is native to South America.
I recommend everyone read about the Great Biotic Interchange, which gave birth to Panama and laid the groundwork of the exchange and extinction of many species, specifically from South America.
In summation, North American animals won in the south both plant life won in the north.