"Anarchism is actually the belief that people can live peacefully among one another and aggression is not needed unless you or someone you know is physically attacked."

Surely I can use aggression if someone eats my banana, even if they haven't "physically attacked" me. You can't have industrial civilization if people can't defend their property.

But then it all starts to fall apart. To know whether aggression is permissible in some instance, you need to know whose property was involved. For example, if I believe that Democratically-passed tax laws make the money you owe in taxes no longer your property, then not paying taxes is impermissible aggression.

So this really reduces to "anarchism is actually the belief in absolute individual property rights". But you can't really have such a thing without some particular theory of such rights. So how does a person acquire a right to property?

If, for example, I believed that all humans have an equal right to all property and if you want exclusive use of property, you must buy it over time from everyone else, my understanding of what constitutes aggression is going to be radically different from yours.

Practically nobody believes it's right to use force to take what you are not entitled to, we disagree over what people are entitled to. And it's dishonest to say that your position is the one that means we don't use force to take what's not ours because almost everyone will claim that's true of the system they advocate.