There is very few NEW creations. In the US, 99.9% of every Spice Rub, Sauce Recipe or any dish for that matter, can be traced back to some origin, either in the States, 100 to 200 years ago, if we are talking BBQ anything, or to the countries our ancestors came from, for other dishes. Only Molecular Gastronomy can be considered relatively New, as it was created only a couple of decades ago.
You can't make anything that has not been done before...BUT...You can research what's been done in the past, either by Type of Food, Regional Variations or Country of Origin. Then, to make it Your Recipe, when you adjust, add or delete ingredients to your liking.
My Tangy Finishing Sauce, is a variation on North Carolina Vinegar Sauce. NC Sauce is usually pretty basic, Apple Cider Vinegar, Hot Pepper Flakes, S & P and a bit of Ketchup or other Tomato Product. After looking at a variety of Recipes, I pulled some ingredients from here, some from there and then added what I like. I played with the proportions until I was happy with the result. After posting the recipe on SMF, others tried it, liked it as well and my Tangy Finishing Sauce, took off being shared hundreds of times. Some guy's have taken my recipe and tweaked it to their taste, making it Their Finishing Sauce.
So that's the Secret, do some research, then follow the Recipe As Is, or You Do You, and make it Your Original Recipe...JJ