Check the folder that this came in, read the readme or license file. That will tell you if you are able to use in commercial use.
If you can’t find a provided file, then you cannot use these. The default state of any creators work is copyrighted, unless stated otherwise.
If you’re trying to sell something it should be a creation of your imagination. Don’t try to asset flip your way into some quick cash, this practice is ruining the Indie Game Industry.