Yes, not so humble. But that's why I've been into internal stuffs. And body changes suddenly like a baby suddenly begin to flip, crawl, stand, walk and run. IMH(or dare)O I doubt people who doesn't talk about these changes first.
I think the body changes have more to do with how the qi develops in the body, the type of qi development you focus on (not all are the same) and then how you align those changes to any martial art expression. (again, differences there as well)
Per the subject of this thread - the connection to the ground (i.e. basic peng jin) is one of the very first things you can learn that's intention based and doesn't require significant changes in the body to effectively begin to "use". Jin will be more effectively developed over time and conveyed more powerfully as the body's qi is developed. But at least initially, they can mutually exclusive - with good reasons why you might want to train them as such, even as you work on stuff that brings them together as well.