Is it normal to make stories in your head?

Yes...I would think this is normal.
to make up stories or scenarios in your mind. This is creativity as well...make up a story write it down...draw the things you see in your imagination...

So very normal

Totally normal and if they're good stories why not write them down and see if you can sell them somewhere? You could even do a creative writing course if you're the imaginative person you seem to be

Yes, they're called fantasies and everyone has them....except for the boring people with no imagination.

I do it all the time and honestly it saves me from reality sometimes to just dive into my fantasies.

Ohmigosh! It's totally normal! And fun, too!

When I think about it and approve it, I decide to make a comic out of the story.

I'm currently working on six. One is my own, two are for fandoms, one is my friend's suggestion, one is about the stories I used to make in my childhood, and the last one was my sister's suggestion.

I do this all the time, whether it is a dream I want to happen in my life or a interesting story about a fictional character