In Robert Frost's poem "The Road Not Taken," the speaker is not identified by gender or age because the speaker could be anyone.
Essentially, the poem is about how it is human nature to want our lives to have meaning and purpose. Humans do not simply recount a series of memories, but they combine those memories to tell a story and to teach or inspire others.
The speaker in the poem describes himself/herself as a "traveler" who comes upon a fork in the road or "two road diverged in a yellow wood." The speaker uses imagery to describe the paths in stanza two:
Then took the other, as just as fair,
And having perhaps the better claim,
Because it was grassy and wanted wear;
Though as for that the passing there
Had worn them really about the same,
Upon inspection of the two paths, the speaker concludes that the paths are almost identical: worn "really about the same" and "equally lay." The speaker then choses a path and remarks how he/she will keep the second "for another day," but "doubted if I should ever come back." This is another example of the theme of human nature in the poem. It is human nature to make plans with the best intentions, but we do not adhere to those plans.
In the final stanza, the speaker reveals that humans tend to rewrite their memories to make the story of their lives sensical. The speaker acknowledges that in the future he/she "will be telling this [story] with a sigh"
Two roads diverged in a wood, and I—
I took the one less traveled by,
And that has made all the difference.
The speaker admits that when he/she looks back at this time that the memory will be skewed and rationalized to be a catalyst for change in the speaker's life. But in truth, this was simply another memory; another moment. Frost did not write this poem to cast human beings in a negative light, but he wrote the poem to emphasize how similar we all are. We do not want our good to be interred with our bones (as it was with Caesar). There is a universal desire for our humanity to be remembered.