All I could make out was that she was talking "alpha" in a more general -- and earned -- way. But it still doesn't make a lot of sense. There are no Winchesters left but Sam and Dean, and I don't think you can actually lump them in with the Campbells after the last few episodes.
The first-born thing is interesting, but not as interesting (to me) as why he didn't burn up when he killed Zachariah and saw the angel light, or whatever.