I like the idea in theory, though I'm not sold on the list of animals. It would be a hard sell for casual players...
What about something called "Zoo Essentials" that included five highly-requested species commonly found in zoos that are quite clearly missing from the game (black rhino, dromedary camel, red river hog, golden-lion tamarin or howler monkey, and a walk-through bird exhibit) and a whole mess of new building items (200+) that are "essential" to zoo building. Admittedly, my focus here would be more on the scenery than the animals but I do think the animals could drive this one given how common those are in zoos!
It could include two "vintage"-style zoo building sets with pieces that could be used to re-create zoos and menageries from different eras (envisioning early 1900s and 1980s here). Including but not limited to new mesh/netting pieces, wrought-iron bars, pieces to more easily re-create moats or small concrete pools, rubble items for brick/stone wall sets, etc. Maybe some new pathing. It would also include other "essentials" like pieces to re-create gift shops, carts/stands for food, turnstiles, parking lots, more backstage pieces, etc.
The scenario could be an empty, abandoned zoo that hasn't been in use since the 1970s with older, turn of the century habitats (e.g., concrete slabs with bars, bear pits, etc.) that you need to update to modern standards.