Labor does not give something value. Labor is traditionally needed for the production of goods. This, however, is not what gives it value. What gives a thing value is final product. This is evident by the fact that individuals do not ask how much labor went into producing a good, they only care about the good itself. Labor can be a source of value in the production of goods, both in terms of producing the actual good and in that some people do value labor, but this then means that it is their valuations which matter.
Furthermore labor cannot have any value without land (since it cannot exist), and can have very little value in the absence of capital. Therefore it would be just as correct to talk about a “land theory of value” and, practically speaking, just as true to talk about a “capital theory of value”. In the ERE, an economy devoid of change, ultimately all prices result themselves to the costs of production, but these costs in turn, for all the factors, not just labor, are determined by their oppurtunity costs elsewhere, which amount to what the individual is willing to pay for the final product. Therefore, although it is all very interconnected, labor, and all other factors, ultimately obtain value on the market from consumer expenditure. You could produce a beautiful and unparalleled work of art every five minutes, yet this would be meaningless, in terms of market pay, if no one wanted your works of art, unless someone valued your skill in and of itself, rather than the product.
Even Marx, it would appear, had an implicitly subjectivist theory of value, since he claims it is only the fact that utility was produced which even allows work to constitute as labor. See my post here. It’s also important to note that Marx’s idea of an average socially necessary homogeneous unit of labor which ultimately determines price is just… Messed up. There’s no way to even argue that this is the case, Marx simply asserts it and I’ve never heard a compelling defense. It’s such a vague concept that it’s hard to know why it would be correct. If I’m a business owner and I’m looking to make profit then I don’t give a damn about averages or socially necessary time, I only care about how much I can earn off of hiring a unit of a factor of production as opposed to how much it costs me to do so.
We see two definitions of value: physical value and market value, what actually creates a good and what it sells for on the market. In the physical sense labor does create value, but it’s not the only thing which creates value. Indeed labor by itself can make nothing. In the absence of capital it can physically make practically nothing, although it could produce services in a decent manner in some cases. Therefore labor cannot itself constitute as its own theory of value, we have to look at a “factor theory of value”, which is exactly what we do look at, that’s precisely why they’re called “factors of production”! In terms of market value all that matters are the valuations of buyer and seller. This would lead us to at least a subjectivists, and most likely a marginalist, theory of market value. This is because we can tell through praxeology that expended labor cannot cause people to do what their values don’t bring them to, only their values can change their action. Therefore individuals value physical goods, not expended labor. This valuation as opposed to money seeps into the price of labor itself, but the source is subjective valuation, not labor.
Does this answer your question?