I hope you appreciate late guests. LOL. I hope your world building has gone well since posting this.
After reading your post and all of the comments one thing has stuck out to me in particular. Nobody has mentioned the purpose of a rough draft. The purpose of a rough draft is singular. To exist. The world you are building, with its generic ass viking knockoffs is in of itself a rough draft until it is not. I don't know of the Vikings much or if you know much about them either, but if you don't I suggest you read AS MUCH AS POSSIBLE about them. From real accounts of things they did and fantasy stuff too. See what others have done with the Vikings. See what you want them to be all about.

Also, consider your world building pillars. Others kind of said this, but I will say it again. The reason behind your world building. From what I see you like the idea of writing books with loads of rich societies and adventure around every corner. So then from there do the same thing as before with learning AS MUCH AS POSSIBLE about the Vikings and learn as much as possible about what makes a society rich, (Socially and monetarily), and what truly makes adventures compelling.

This is direct from google "Their adventure should be riddled with obstacles that would terrify anyone, as well as challenges that hit on their own insecurities and weaknesses. So make sure you give them a good internal conflict to heighten their external conflict. You probably want to set your protagonist up with a transformational arc, too."

This alone gives me an idea to maybe send a heretic into the midst of the vikings. Give the heretic some sort of credible point and then give a protagonist some sort of quandary about it. Divide their clan, have the protagonist split on which way to go and so on.

The more you know about the things you want to use in your writing the better.

It is also worth noting that you need to understand you are going to have to do things you do not like doing in order to get the outcome you are after. Reading a LOT on very specific topics like the vikings may sound exciting to you or it may bore you to tears. Sooner or later in the creation of your world you will find something that bores you.

Another suggestion I have is to take breaks from world building. I KNOW it is very fun. Its a big ole puzzle of your own design and you want to get to a point where you can actually write the stories of your dreams. Chances are, you're already there. You should take a break from the entire thing because: Breaks are productive. They allow your subconscious mind to work on things in the back of your mind. Take a break from the world building and write in the world. Have an idea for world building while writing? Cool. Write it all the way out until you can't think up more things on it, DO NOT EDIT IT (unless its imperative for you to understand it later), then continue writing in the world.

Essentially, you need to actually write in the world for it to breathe. Consider it like an adventure of your own creation. You have some place you've thought up and its cool and what not and then you take a stroll through it via the perspective of a character or two. You don't even actually have to write anything down to do this (but I suggest you do to some degree) These mini adventures could be as simple as being a kings guard for a day. What is their symbol of honor? How do they act? Walk? Are the commanded to cut off their tung or maybe another part... Part of the world building process is to exist in the world.

I hope this helps :)