I knew that water slide would kill someone.

[abaris]

I still encourage her to go have adventures on her own, but she will always be correctly seatbelted in a car, helmeted on a bike or scooter, and supervised while playing out of doors.

You know there are sane protections. Such as seatbelting your child or having an eye on her when being outside. My father even installed a seat belt in the backseat of his car for me to be protected. That was back in the early 70ies when only nerds and professional race drivers used seat belts. Way before child seats were even a thing. That's a valid approach, and remembering it saved my life later on when I, driving on myself, got into an accident. I was belted in, though it still wasn't that common in the early 80ies.