Among the many things I don't understand is why I even bother to waste my time explaining anything to someone whose apparent sole purpose in life is to pretend that they have won arguments through the remarkable tactic of giggling at anything the other person says, whether they understand or not (and, almost invariably, not).
Be that as it may, let's at least make a few points clear:
1. The "happy chemical accident" is not an accident of "happy chemicals", but a "happy accident" with chemicals involved. I'm pretty sure a ten-year-old can understand that. It's also pretty uncontroversial that it's "happy", because we wouldn't be around otherwise. Then the only debate is over whether or not this was an accident after all, not any of the adjectives attached to the process.
2. There is actually some good reason to think of it as somewhat accidental. Not so much the earliest forms of life on Earth, whose origin might be better described as a "happy chemical inevitability", but certainly the origin of complex life smacks of "accidental", because there is no reason to suppose that Eukaryotic cells have to emerge as an inevitable consequence of anything. Still, this remains an open question, of course.
3. Why are you so afraid of open questions in Science, anyway? It's a simple truth that we will never know everything about where we came from, what we are doing, how we work, how the Universe works, etc etc. But so what? That just means that we'll never run out of new stuff to learn.