Most property in the world can be traced back to an original owner, from whom it was stolen (war, colonization and similar events). That original owner might have stolen it from someone else.
But that is a completely different point, that really has nothing to do with libertarianism, or any reasonably capitalist society, where property ownership is permitted. It's my impression that a symptom of a mature capitalist society is that historical property disputes are settled in a sense that can be considered fair. That someone might not accept property rights is an interesting discussion, and it certainly rules out any form of capitalist system, but it doesn't really apply in this discussion.
Nobody is born with a right TO anything, but rather a right to NOT be coerced. The consequence of this is that you have the right to do whatever you want with your property (which includes your body and anything you do with that, i.e. work), as long as you don't interfere with other peoples right to do the same - i.e. coerce them.
One important distinction between libertarianism and anarcho-capitalism is how to resolve conflicts that will inevitably be over property. A-C doesn't accept any state-like structures like police and courts, but libertarianism does, and the only people that get to coerce other people physically are the police, answering to the courts.