I think you misunderstand the Cosmological argument (for the record, I'm not arguing for the existence of any gods as I'm an atheist too, just trying to further the understanding of what the Cosmological argument really is).

The CA doesn't really fail to answer the question "who created the creator", it states that, for the universe to exist, there has to be some kind of "unmoved mover", some ultimate first cause/level of existence/etc. that came "before" (not necessarily in time) everything else. This conclusion seems hard to escape to me, as even an infinity of causes that resulted in the universe could, in some sense, be seen as this kind of ultimate first level of existence. That thing is what shall be called "God".

Even as an atheist, you shouldn't have much trouble with this kind of argument up to this point. You might not agree that an ultimate cause is necessary, but at least you seem to agree that it is possible. You seem willing to accept the Big Bang as a possible ultimate cause. You'll probably disagree with the practice of calling this possibly non-personal cause a "God", but that's just arguing over which sounds to assign to a certain concept.

This is where the problems with the CA start, since this is where the theist has to give reasons why the ultimate cause has to be personal, and actually even has to be their own God. Basically, the theist will now go on to list a certain number of properties that the ultimate cause must have, and that, according to the theist, their own version of God traditionally is also said to have. I won't bother with most of them, since the ones I've personally seen were obvious bullshit and rely on severely redefining most of the terms. I'll instead try to explain the one that is at least kind of hard to counter, which is the claim that the ultimate cause must be "personal", and thus a theistic God.

Basically, according to the CA, the ultimate cause existed for a while (we don't know for how long), and then suddenly created/caused the universe. The ultimate cause must be unchanging according to the CA, or it would... constantly churn out more universes, I guess? I'm not really sure why. But yeah, it must be unchanging. But it must also be able to, at some point, create the universe, even though it hasn't done so before. And how can it do that? Well, the only thing that can be unchanging, and still do something new, is a "personal" being, that suddenly "decides" to do things. QED GOD!

Well, that's the Cosmological argument as I understand it. The problem of course is, that a personal being does change. Every decision you make, every thought you have, changes you, and only the childish belief in a magical soul can save you from this - but even then only if you completely ignore the fact that, even if your thinking is magic-based, your character still changes with every single thought. Magic is simply no remedy for determinism.
The other problem is that even if we do include the arguments for a specific God that I have left out before, those arguments never become specific enough to actually prove the Catholic God or the Mormon God or any other specific God. When I saw those arguments, I have to admit they reminded me more of Lawrence Krauss' idea of nothingness than the biblical Yahweh.

And this is why I think that, in the end, "Flying Spaghetti Monster" is a perfectly valid response to the Cosmological argument. Because it really does fit FSM just as well as it fits Yahweh.