I use unren 1.0.11d to extract images from this game but it only comes with thumbnails and images without background. I have almost all BigBrother, which option should I use to get normal game images?
There is no such option.
These are the layers which the ingame images are composed of.
Background + Naked char + Clothing = finished image.
This allows for example clothing variarions without having to store the almost same rendering multiple times.
What you can do is to use a software that supports multiple layers and webp, then combine the images yourself as you like.
Btw, maybe this time you actually bother to read the answers to your post? Lukumoide already explained what I just explained again.