This is just nitpicking. The wealth differential produces by the ox for 15 years of its useful life requires very little extra labor from me, the ox raiser.
That's why they have a category for "capital". If some people build a factory, it is technically labor, but it will be enabling the creation of extra wealth for decades, to some extent centuries. Who should get this wealth? The labor 50 years later working at the factory has no moral claim on it.