So, if I jailbreak my iphone i'm basically granting permission for all users and apps to run as root on my phone, is that correct? If that's true that can't be good. I don't know so someone please enlighten me.
JBing just allows non Apple signed code to run and grants access to root. That's it. You do need to be careful with what you download from Cydia but most apps and tweaks are fine. Just be careful when adding non trusted repos.