People still jammin Brenda's got a baby? Pretty sure I havent heard anybody bumping that since MTV2 did a Oldies lineup. Even most those songs listed by the thread starter I'm sure majority of people under 24 dont find timeless or relatable and actually probably label it old shit. People who grew up to that shit going always have a biased feeling that the songs they grew up listening too are "timeless". Its all a age thing, but like somebody said when it comes to love songs usually they get a easy pass between age groups because people love those type of songs no matter the decade but RAP is another thing.
There is no right or wrong answer because sounds change. I can probably say love songs are probably the only real timeless genre.