If we are being annoyingly accurate, labor-power is a commodity to sell from the perspective of the wage-laborer, but capital in the hands of the capitalist. The wage-laborer sells their only commodity, labor-power, for a sum of money, to then buy their means of subsistence in the form of other commodities thanks to money’s use as the universal commodity. From the capitalist’s perspective, though, they use money to buy means of production and labor-power as commodities, then through combination and production, they are used as capital, to then be sold for greater money thanks to the surplus value created.

From the wage-laborer’s perspective, it goes commodity -> money -> commodity. But from the capitalist’s perspective, it goes money -> commodities -> productive capital -> commodities of higher value -> greater quantity of money.

In simpler terms:

Wage-laborer: C-M-C

Capitalist: M-C(mp +L)…P…C’-M’

Something isn’t capital just because it’s used for production. Something being capital is a social role, and is fundamentally tied to production from the perspective as a capitalist, as something participating in this circuit of accumulation, not just simple commodity production predating capitalism.

This is why the wage-laborer has no ability to endlessly expand their money in a greater and greater fashion, while for the capitalist this circuit must repeat itself for there to be commodities for the wage laborer to buy. This is how they steal surplus value, why capital grows, and why it concentrates and centralizes while disparity rises.

The wage-laborer has no capital.