Our speaker sounds a bit nostalgic and reminiscent over his youthful and foolish days of refusing to take good advice in "Down by the Salley Gardens." So we know for sure that he's using a retrospective kind of first-person voice. And since the ballad sounds so rhythmic and lyrical, it's easy for us to fall right in line with his reminiscing about the past.
We might even imagine the speaker reciting the ballad in a pub or living room somewhere in Ireland, since his story sounds like such a common one. He sounds familiar to us not just because of the actual story he tells, but also in the way he uses simple down-to-earth kind of language. Idioms like "take love easy" and "full of tears" aren't exactly super-advanced poetic expressions. Rather, they're down-to-earth ways of describing his mistake. We see the speaker in a common, accessible way, a regular Joe who can admit when he made a mistake.
And since he sounds so familiar, it's not as if he sounds pretentious or self-righteous about the kinds of lessons he's learned. Instead, it's as if he's looking out for the rest of us by letting us know that being too pushy and eager is totally common when you're a young boy. Maybe, with all the natural imagery we see, he even makes it seem like youthful foolishness is completely natural and part of growing up—even if it does make you wind up bawling your eyes out in a public park.