I've got two kids under 10, although I see the rating for Creatures Village is 3+, just how easy is it? Simple enough for a six-year-old to handle? Is it impossible for truly awful things to happen to the Norns? (Important in this case, we're talking two little girls who flipped out when their dad was trying to teach them a horse-riding video game, the horse stumbled and they lost a life... "AAAAAGHH!!!!! Daddy killed our pony!!!!")

I haven't played Creatures Village myself but I did play creatures 1 and 2 when I was younger. I was probably closer to the age of 10 but both of my brothers played it as well and they were 2 and 4 years younger then me. I don't even think I completely understood the game but I had fun with it just messing about. The Creatures Village is meant to be even more kid friendly version of creatures so I would think your children should enjoy it.
I honestly don't remember if 1 or 2 had any awful moments though. I was playing games like doom when I was young as well so a norn falling over or something wouldn't have even registered for me.

The creatures can die of disease, drown, and even get eaten by pirhanas in Creatures 1, 2 & 3, but I don't think that's the case in Creatures Village, which is really oriented toward younger kids..

Thanks for all the answers, I gave the rep to Amaikokonut because that was the most specific reply to the bad-death part. :)

Creatures Village is a combination of the two games in the series that were specifically aimed toward children ages 6 to 9.