Have you tried to enter the category (Wordpress, HTML etc) and then did a category search for “Advertising”?
Alot of the themes these days are very fancy, creative and responsive because this is how the web is developing.
Many themes also comes with a lot of features that you might not need…right now but later on you realize that it might could come handy.
I hope you know that even if you bought a theme that is “too” fancy or creative, you can still change this. Just because you bought a full featured theme doesn´t mean you have to use all the features. And also, you can customize it all just the way you want.
Have a good day!