Using !important you increase the priority of the current selector. At the same time, the importer does not affect the style inheritance rules for the child elements.
For example, if you have a page somewhere above your code style:
body#dumbid{color: orange;}
And you cannot change it in any way or somehow change the markup to get rid of it, in such a last resort you can use !important to override it, or duplicate the selector to equalize the priority.
body{color: blue !important;}
So you only neutralized the body#dumbid , but did not change the inheritance rules for the child elements.
In your case, it does not matter if there is an !important or not body style. The p selector will take precedence since it is more specific.