I hope so, but short of a time machine or aliens telling is it was them, I suspect will remain hypothesis as to how it happened.
Yes they do. My basis was above but: All the ingredients for life are common in the universe, planets are very common, and when you're talking about numbers like that, the likelihood or "odds" of us being the only intelligent life is considered darn close to zero: "The Milky Way Galaxy alone is home to between 100 billion and 400 billion stars, and each is potentially orbited by planets. There are probably at least two trillion galaxies like ours in the observable universe, each one populated by trillions of planets orbiting hundreds of billions of stars."
When working with those types of numbers, the odds of us being alone are as close to zero as one could ask for short of confirmation. That's the common and accepted view among most scientists in the field currently, and it only gets more robust. One can put the most pessimistic of numbers for example into the Drake equation and still end up with thousands, if not millions, of planets with intelligent life.
We have literally just started looking in any real sense of the word, not even a cosmic eye blink time wise. It's all speculation until it's not. We now have major resources and very smart people looking both far far away and locally, and that's very encouraging. As Clarke said:
"Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying."
Arthur C. Clarke