Of course it is. You asserted that by my definition every human was a slave. This is obviously false since there is a minority that managed to free themselves from this suffering somehow. They make others do the work for them.
Of course, technically you're right - there will always exist a minority of people who were so wealthy (and lucky) that, even though they didn't care about wealth preservation, their wealth didn't run out before they died. If, in addition, these people inherited all their wealth (as opposed to doing any work to obtain it), then they are the (only) non-slaves by your definition, proving that not EVERYONE is a slave.