Singing is the art of sonic illusion, presenting or perhaps even 'implanting' a feeling in the listener. The singer might make the listener feel like they want to scream or cry, but that's not what the singer herself is doing. That's the effect the sound has.
So what we are doing is creating something that is not what it seems, but which conveys emotion to the listener. The meaning of the lyrics is always secondary to the emotion. The meaning gives rise to the emotion.
Singing is not the correct medium for communicating the literary meaning of the lyric. I could give you some lyrics and you could read them and understand the literary meaning. Say it's a song you've never heard, or that has hasn't been written yet - we've just got a lyric. You read the lyrics, and understand the meaning through the medium of the written word.
The art of the songwriter (and poet) is to select the words so the the sound that they make is equal to, or perhaps we could say 'expresses' the feelings engendered by the meaning of the words.
So we can put the literary meaning aside and deal just with the sound... the singer then has a template that they can use to create a soundscape which conveys the emotions engendered by the meaning of the words. And we give that to the audience.