Humans cannot fathom infinity. Go ahead, try it. Imagine a hallway forever long or count to infinity. We can qualitatively analyze it, we can even use it for advanced mathematics, but we cannot understand IT directly.
That being said, I also cannot understand nothing.
No, not black, you're imagining black. No, not 0 either. Outer space? Nope, that's still area, volume, and radiation.
Even if you got past those previous examples, YOU would still be there observing it so you're still there. There's still observance.
You can't comprehend it because it is the same thing as infinity, except worse. At least you can imagine part of infinity.
That being said, I believe it is infinite. If it had spontaneously started, there would have to be something before that to create it, something before that to create that, etc.
Perhaps there was nothing, but if that was what it was, I couldn't possibly believe in it because I cannot even comprehend a single dimension of it.