The principle
What makes some questions about song lyrics off-topic is that they don’t seem to have any real, definitive answer, only interpretations that differ from person to person. An on-topic question about a song lyric asks people to explain something about the English language or how to make use of the lyric as part of the process of learning English.
A common mistake
One comment said the question was about how to interpret song lyrics, which he thought was “subjective”.
I think that interpretation of your question was just an inadvertent mistake. I understood your question to clearly be about the “I am he” construction, how or whether it shows up in that sentence, and why you would or wouldn't include commas between each instance. You had been wondering about that construction, searched for examples of it, and found a doozy. A couple of the answers listed various trivia about the song or speculated about what the meaning might be—not even the meaning of the sentence you asked about, but the meaning of other verses in the song!
I've seen a lot of answers like that, that wander off what the question was about and never get around to answering the question. In this case, it appears that people may have mistaken their own wandering off-topic for the question’s being off-topic! It happens.
Before asking
So, before asking a question involving a song lyric, I suggest thinking of how to word it so it’s clearly a question about learning English and not a request for people to give their own, individual interpretations of the song’s meaning. If you can state explicitly what aspect of English that you’re hoping the song lyric will shed light on, that will help. Asking what the lyric “means” can trigger people to think you’re asking for “subjective interpretations” even if that’s not what you intend. Here are a few ways to steer readers away from the “subjective interpretation” interpretation:
Why does this song lyric violate the usual rule for ____?
What does ____ refer to in this context?
[Element of grammar] in ____
Does this phrase have a clear meaning in English?
How does a native speaker make sense of this phrase?
That can be very difficult, of course: the reason you’re asking the question is because you don’t clearly understand what’s going on yet. Sometimes the real meaning of a question can only become known by answering it. For example, the song lyric you asked about had both “I am he” and “you are me”, seeming to follow two different rules. TRomano’s answer addressed that. But if you’re the one asking the question, you might not be able to see in advance that that’s what your question is really about! So, sometimes “What does it mean?” is the clearest way to ask an on-topic question and you have to rely on the answerers to figure out what you're getting at.
Fortunately, when people vote to close, they often add helpful comments about why, like the comment you quote. You can use that information to alter your question to clarify what aspect of English you’re interested in. The comments themselves often contain clues to what that is.
Before voting or answering
For answerers, I suggest considering the following before voting to close a question about a song lyric—and also before answering it:
Is there a way to interpret the question that is on-topic?
How can you answer this in a way that helps someone learn English?
For example, could it be a question about grammar, vocabulary, idiom, or how a native speaker makes sense of figurative language?
An important part of learning English is learning the common cultural knowledge that speakers assume when choosing their words in order to be understood. So, it can be very helpful to point the reader to the relevant cultural knowledge and state specifically that it’s common knowledge—or that it’s only common knowledge in one region, one specialized field, etc. It is off-topic to describe esoteric trivia that doesn’t shed light on how a song lyric communicates or fails to communicate.
“Objective” questions about “subjective” interpretation
If a song lyric is “subjective”, which I take to mean that different people understand it differently because it’s unclear or ambiguous, then that might be the answer, together with an explanation of why it's unclear or ambiguous. Just because the song lyric is open to widely varying “subjective” interpretations doesn’t mean that the question is “subjective”.
It can be very helpful to an EFL learner to present the facts about grammar, vocabulary, and common knowledge that explain why a native speaker finds a song lyric incomprehensible, unclear, open to two parallel interpretations (like a double-entendre), or rich with emotional overtones. For example, if a song lyric sounds similar to two common constructions that are familiar to English speakers, but doesn't quite match either one, causing the confusion, it can be helpful to explain that. This kind of answer is about English, not the song. That’s probably what the person who posted the question is hoping for. (If not, then maybe the question really is off-topic.)
Note also that on ELL, we want certain kinds of “subjective” questions, because we want answers that explain why rather than just state a correct answer. More about these “good subjective” questions is here. When native speakers describe what happens in their mind when they make sense of a phrase, they’re describing something “subjective”, and not all native speakers will see it the same way, but this is itself useful, factual information for someone learning English.
