I tried preemptively euthanizing all Animals (Spoilers)

[Jewel the Espeon]

I got annoyed by the protagonist lack of survival instinct and decided to play as sane und reasonable as I could. So as soon as the first mutant showed up, I made a bunch of lethal injections and started systematically killing everything.

It didn’t work. Parasite somehow seems to know what I am doing und transforms right away, as soon as the first animal drops.

I just don’t get that from a narrative perspective. Are the Parasites intelligent? Can they transform whenever they want to? If they can, why are the pretending to be normal animals at all?

Why doesn’t Doc care, if I do the opposite of what I am supposed to do? Wouldn’t killing all the Zoo-Animals interfere with his plans?

Why do I still have to give Meningitis-Medicine to the Wallaby, after his buddy mutated and tried to kill it? The priorities of the protagonist are really something special.

[Meanator]

My best guess for why they pretend to look like a normal animal is similar to why players in prop hunt pretend to be a regular prop.
to keep the hunter from finding the fake and dealing with it.
as for it's intelligence I would probably say assuming the trailers are a demonstration they are smart enough to hide and ambush but not smart enough to open doors or be reasoned with.