The Subjective Nature of Myth

When reading Barthes' Mythologies, I was somewhat confused about the nature of myth, particularly whether or not it is subjective.

On page 116 when describing the picture of the French soldier, he writes:
"On the cover, a young Negro in a French uniform is saluting, with his eyes uplifted, probably fixed on a fold of the tricolour. All this is the meaning of the picture. But, whether naively or not, I see very well what it signifies to me: that France is a great Empire, that all her sons, without any colour discrimination, faithfully serve under her flag, and that there is no better answer to the detractors of an alleged colonialism than the zeal shown by this Negro in serving his so-called oppressors."

His use of the first-person pronouns "I" and "me" brings forth a few questions. The signified is what Barthes describes as his personal perception; the language he uses made it difficult for me to view the signified as an objective entity (As a side note - the whole emphasis on language and connotation in these readings gives me intense anxiety regarding my word choice). Barthes then uses the words "signified" and "concept" interchangeably, but in the language the concept is more concrete than the abstract and mental signifier.

I guess my question is if a myth is so largely composed of what we perceive as the signified, then how can a myth be as objective as Barthes seems to insist that it is? From my reading, the myth seems to be entirely more subjective, more mental, affected by so many more variables than language. The myth seems to be somewhat metaphysical by nature, which, Barthes states, semiology is not (112).