I assume that cause and effect applies until demonstrated otherwise. This leads me to a first cause, although I make no assumptions about the nature of that first cause. Perhaps it's a cosmic foam, or God, or Azathoth, or Haruhi Suzumiya, or something we simply can't imagine.
What caused the first cause? Well, nothing. It's eternal. In that respect it would be weird and incomprehensible. On the other hand, the alternatives would also be weird and incomprehensible, so that's okay. For example...
- An infinite sequence of cause and effect. The obvious problem here is that with an infinite chain, we would never arrive at the present... unless at some point the sequence passes outside of what we conceive as spacetime, in some weird and incomprehensible way.
- A finite sequence of cause and effect in a loop. The events at the end of the universe cause the beginning of the universe, through some weird and incomprehensible means.
- At some point there was an effect that was not caused. It just kind of happened spontaneously, for weird and incomprehensible reasons.
Every explanation has something weird and incomprehensible attached to it, so logic fails us. There are fundamental aspects of the universe we're still missing, as fundamental as cause and effect. Until we identify those fundamental aspects (hopefully without going insane in the process), we can't apply a good sequence of logic to the question of how everything came about.
I certainly don't see how logic could lead one to the idea that a first cause would have to be omniscient. In fact, my first pass at logic on the situation led me to the conclusion that a first cause must be non-sentient, although I was working with the questionable assumption that consciousness itself must always be a sequence of cause and effect.