Here is what I think is behind a lot of very good and very lasting songs....adhering to these policies (see I didn't call them actual rules..) won't guarantee the song is good but I think it will very much increase the probability of it being remembered and sung..
1. Use short, conversational words mostly of one to two syllables.
2. It has to rhyme (well, not really has to..) exactly and perfectly, about 98% of the time. Every now and then you can misrhyme a little bit.
3. It does not have to follow rules of grammar.
4. The meter has to be 98% perfect..and occasional deviation is OK but never more than one in the same song. Never cram excess words into too short spaces. Think of it like old fashioned typesetting..there is a space for a word or words with a particular meter. Don't put something in there unless it fits.
5. The tune should be singable by others..not too great a range.
6. It does not have to tell a story from start to finish. It can start and stop in "media res". People don't have to figure out or know what it means.
7. It really helps if you name the name of the person and the location and give an idea of the time. "My name is Yon Yonson I come from Wisconsin..my name is Peter Amberly.." Universal songs are less memorable than time and place and person-specific songs and are ultimately more universal.
8. Leave blank spaces rather than put in words that don't fit the meter or otherwise fit. If you can't fill in the blanks, ask for help.
9. Each song deserves its own tune, although sometimes they just jump on to another one. If you can't write tunes, collaborate. Don't put them to the Star of the County Down, Tramps and Hawkers or Silent Night.
10. It can't be too short but it can easily be too long. It can't be too simple but it can easily be too wordy or complex.
Just look at the songs that have survived...I bet most of them follow these..suggestions..