I know it's hard to explain. However, it's all about quality of the light, whether it is natural or flash, whichever. For a portrait photo, soft and directional light is "usually" the best light for a subject, particularly in a female, or kids .
Yes, some photos you post were in wrong white balance setting, which is another thing you will need to learn so my suggestion is shoot in RAW so you can easily fix it in pp.
These are the shots of my kids taken 4-6 years back. Tell me if you know which one is shot with flash. Hint: only 1 taken with "bounce" flash
This is just my opinion, but the above examples are what you should be paying attention to. The other ones given, shown, used as examples leading up to the post are over processed and very poor indeed.
It is indeed all about the quality of the light and where it comes from in relation to the subject. You are after all, painting with it.