You will need to:

1. say what style you are using; and
2. Better describe which Zotero fields contain the names.

In my English-language version the name labels last (name), first (name).
What you are using for name labels seems to be your translation from your language to English. Please tell us the name labels in the language as you see them in your version of Zotero.

If you mean:
Last = Simon
First = Conway Morris

then I'm puzzled with how you are getting "Simon C. Morris"

However, see my note below because this may not be the correct way to enter the name(!).

Is a citation style you developed?

Are the author's names entered as two fields or as a single field?

Could you have more than one Zotero record of the same item and you selected one that has an error in the name fields?

If you are citing the paleontologist, his name is:
first = Simon
last = Conway Morris. (a double last name, in his case not hyphenated)

Since the gentleman's first name is "Simon", I believe that you do not want "Simon, CM"

I can't replicate this with ACS style and that name. How exactly are you testing? What happens in a new Word document? What happens when using right-click --> Create Bibliography?

OK, that I can replicate. There's nothing in a CSL style that'd change this, no. Is there an example of this, though, that isn't a typo? I think lowercase words aren't initialized on purpose to deal with name particles, but it's certainly an edge case -- but I'd imagine a very rare one?