Well that's true, considering you wouldn't be eating
anything. Everything, plant or animal, contains some Omega-6. It is an essential fatty acid, you must have it.
You seem to misunderstand some of the key concepts of Lipid and Biochemistry.
I broke down some of the components of the Fats in Human Adipose tissue in this post.
What is Human Fat?
This also applies to fat from food, it's all the same.
Omega-6 (18 chain with a double bond in the n-6 position) is one of two kinds of fatty acids, that we can not produce by other means, that we need in order to function properly.
Omega-3 (18 chain with a double bond in the n-3 position) is the other.
We do
need to eat both of them. The issue is that they compete for receptors and if you have too much of Omega 6 or Omega 3 (although it's always too much Omega 6) it can impair the function of the other.
In other words your conclusions about fatty acids are incomplete and not well informed. There is a ton of information available on the internet, or if you take a basic organic chemistry class.