The whole "who created the Creator?" response has always struck me as a red herring and non-response/nonsensical. If X created Y, then the question who created X, even if left unanswered, would not change the fact that X still created Y. But besides that, pretty much everyone understands "God," however defined, as a noncontingent being, and a non-contingent by definition can never not exist, and is an uncreated, uncaused ("prime/first mover") cause as a matter of course. Now someone may complain that this is convenient, but those who do so, still end up postulating their own non-contingent, uncaused cause (such as a "universe" or "multiverse" that has always existed). Whether one adopts metaphysical naturalism or supernaturalism, an infinite regress of endless causes doesn't make sense. Ultimately, it would seem we have to ground reality in some initial, uncaused non-contingency, whether that be the "universe/multiverse" or God.
It isn't the understanding of what the word "God" means (and you are choosing a meaning not everyone gives it) that puts God beyond the asking of the question, "Where did God come from?" What does it is first, asserting that there can be no causal or explanatory loops or infinite causal or explanatory chains, so that any causal or explanatory chain must have a terminator (so that, in particular, the causal or explanatory chain involved when inquiring as to the cause or explanation of the universe's existence must have a terminator), and then, second, labeling that terminator "God." But if one does so, then in order to avoid equivocation, he must make the word "God" *mean* "the terminator of the causal or explanatory chain (in particular, the one involved when inquiring as to the universe's own causal or explanatory chain), whatever that terminator might be"--and then *NOT ALSO MEAN* "a sentient/sapient being who cares about humanity, listens to prayer, has a divine plan, sent his only begotten son to Earth/spoke to Mohammed/appeared as a flaming bush, decides who gets into which afterlife (assuming there to be an afterlife), and so on." One cannot simply assume that the terminator is the being which he conceives God to be. As you rightly note, one is free to dream up his own terminator--but one may *not* simply assume that the terminator is whatever he chooses it to be, and one may *not* place his own chosen terminator beyond such questions as "What caused it" until he has established that his chosen one actually *is* the terminator.
Lets ask a serious question. We have two theories that attempt to explain our origins. Creation says an intelligent designer created and designed the earth to support life. Evolution says it happened by a series of accidents. Be honest. Which one makes sense? Isn't it obvious that somebody had to have done this?
Look at the beauty and the symmetry--yet with endless variety--of snowflakes. Look at the beauty and complexity of the stalactites and stalagmites in crystal caves. Look at the regular shapes of the geological formation known as the "Giants Causeway." Isn't it obvious that somebody had to have designed and made each of these? Well, no, it's not. What you would label "accidental events"--what I would label "events occurring in accordance with natural law and therefore not fundamentally accidental"--led to all of them.
"It's obvious" doesn't always turn out to be true.