There is a constant parenting dance we do as soon as kids start to get mobile and that is the exposure-safety dance!! There are as many opinions as there are experts. SO much comes down to your philosophy and view of the child.
If you see the child as competent and capable you will allow them to be in SAFE environments where they can learn to climb and take risks. I’ve visited some amazing forest schools where children are free to run and climb and develop these skills early on. However, some parents would object that the logs are too high or the hill too steep. They may have a view that the child needs to be taught everything, adult led and bubble wrapped so they don’t experience any pain or frustration.
My tendency is to always make sure environments do not pose developmental risk (eg. sharp objects, long scarves etc.), and let the kids explore with an adult present to step in if needed. Kids hurt themselves less in outdoor classrooms than indoors, so I’m told… developing competence perhaps.
With regards to walking home alone at 6. I’d need to know the conditions, my tendency is to think that if a child has others they are walking home with, it is a short distance and you have caring adults along the route they can turn to, then go for it. It develops their sense of mastery. But if they are a very young 6, not mature enough to appreciate risk and danger, then they would not be ready in my books. There is a very big development growth between ages 5-7 and each child is unique.