How many items in a list can a human create without repetition?
Recalling items from short term memory is a very different task from creating a list of all unique items. There are a number of strategies for recalling items from short term memory without repeating, you can remember all the items in the list in a random order and all the items you have recalled or you can remember all the items in a fixed order and where you are in the list. When creating a list of unique items you need to create a rule, remember this rule and the number of items you have recalled. The list itself is in long term memory

For example, if you are name as many numbers as you can without repetition, you could say the positive integers 1, 2, 3, ..., N. Equally valid would be the even positive integers 2, 4, 6, 2N. You could also list the Fibonacci sequence 1, 1, 2, 3, 5, ..., $\frac{\phi^n-(-\frac{1}{\phi})^n}{\sqrt{5}}$ or if you know them the digits of $\pi$ 3, 1, 4, 1, .... In all of these cases there is a limit to how far you can get since you need to remember the number of items you have given.

Numbers are obviously easier to create rules for than animals, but for animals you could do something like ant, bat, cow, dog, eel, fly, ..., zho, anoa, bear, cuis, deer, ..., zobo, addax, bison, camel, dingo, ..., zebra, ...  I am not sure how far one can really go with this rule, but it will get you pretty far