I have two kids, 5 and 8 years old. Each of them have a Ball Python of their own that they are able to handle easily and I feel very confident each time. Your 6 year old will want to be involved and you will want him to be.

I now have a Bredli for myself. The kids are fine with not handling him at the moment because they have their own. It would have been difficult to start with anything else that wasn't a known "beginner" snake with the kids as curious as they are.