What can I sell in marketplace?

I have a lot of assets in my library, most of them I have bought or gotten for free. I believe I can create environments or houses etc with all the assets I have gathered. My question is will I be able to sell what I create?

Do I break any rules if I use for example I use a furniture pack that I have bought, fill a house I created with said furniture, and then sell it as an environment?

Read the guidelines, all of them or at least the ones relevant to the content you want to sell.
You absolutely need to follow these if you wish to sell on the marketplace.

In this case you will break all possible rules. You cannot redistribute the assets of other sellers, you can use them in your game, but you cannot resell them. As someone else already stated read the Marketplace guidelines.

I tried reading them but I can’t completely understand them since this isnt my first language. This is what I cannot understand: I get it that I cannot take two different packs that I have bought, and then resell them since that would be illegal and immoral. I understand that I can use the asset packs to make a game and sell the game. What I would want to do is create an original map of my own for example a wild west town, then sell the map. What I want to sell is my creation, but since that creation is made from other peoples work I dont want to “steal” their effort. I dont have the necessary skills to create detailed assets that’s why I am looking for a solution that works. If you know anything more pls explain as simple as possible.

I have replied to another comment about the guidelines could you please check it out if you have the time?

I seriously doubt that people will be interested in buying pre-made level designs, that is something extremely dependent on the individual game. The environments that come with assets exist to show off the objects therein and offer an example use-case, not to be used as is.
What you’re describing sounds like part of the job of a level designer or environment artist, but only part of it. I honestly do not understand what your goal is here.