Yeah, this seems scary because we have an injury section. What we don't have is a "non-injury" section where people can post and say, "I trained all day today, and my body feels great!" because that is the norm (assuming proper training). So don't let the presence of an injury section deter you.
Train smart, progress slowly, check your surfaces, and examine and respect your natural fear reactions to things, and you will be fine.
Yes, parkour is risky and can be dangerous, but no more so than any other physical activity.
If your bones break easily, you might want to talk to a doctor and/or make some dietary changes to address that.