Here is a small sum-up:
Your description of ISFP sounds far more of a description of Fi.
I don't think a "general" theme of INFPs is people. Hahaha. No.
Also, you have to take a grain of salt in typing other people. Odds are that you are not 100% accurate with every person you label as being INFP or ISFP.
And there is really no way that an iSfp is going to be more "N" than an iNfp. That sentance makes no sense! It's comparing apples to boomerangs. You need a common denominator to draw a comparsion from.