I think what we are getting into here is a question of semantics over the word "labor". Lincoln seems to use it as a verb whereas Marxism tend to use it as a noun.
Lincoln championed the idea that "labor" (v) meant work with rewards that could be accumulated to create capitol. i.e. -- people had the ability and freedom through hard work to advance.
The Marxists saw "labor" (n) as a static social class. In essence, while extolling the "nobility" of labor (n) as a class, Marxists looked down on labor (n) as helpless, unchanging and by definition, exploited, while Lincoln saw labor(v) as a necessary step in moving up the social ladder --- class mobility.
They both could say that labor comes before capital, but they meant very different things.
I think you're right about Lincoln's not thinking of "labor" as a social class, but as human activity. If you want to understand Lincoln's economic views, you have to consider his belief in promoting inventions through patents. There is something Emersonian about Lincoln's belief in what the individual can achieve through work and ingenuity. It is that faith in the individual bettering his lot through activity, ambition and inventiveness, not any utopianism or working class politics or envy that drew Lincoln to the "labor theory of value."
If the kind of disciples a thinker attracts is a reflection on the thinker and his thought, Mises cuts a very poor figure. Refuting the labor theory of value was good work (though I doubt it was Mises himself who did this). But smearing and reviling everyone who came before this refutation because they didn't know what they couldn't know, is pretty low.