Just to be clear, in English, there is a difference between 'classic' music and classical music; Debussy's work being classical.
Songs become classic if they remain (stay) popular, for example, many of the Beatles' hits. The same for literature or clothing. It is why classic clothing can be considered timeless fashion.
Also, the word 'classics' refers to the study of classical antiquity (ancient times), particularly, the Greeks and Romans.
[Have you ever thought what makes a classic?] - Why is something (considered to be a) classic?
I feel classics have especial magic
Because it's safe to have a strong opinion about a classic piece of art. Let's take books because that's my interest: you can love it (and that will prove you're well-read and cultured) or you can dismiss it (and that would make you a learned rebel). Any way - you're good, better than most people who haven't read it at all, you will shine at parties. And what's best of all, most people won't argue with you because even if they read the book you're talking about, they won't remember much about it. So you're basically safe and you have something to brag about. Very handy.
Now, having an opinion about something that is relatively new and therefore of uncertain status - that's risky. Unless of course your opinion is shared by your cocktail buddies.
BTW, don't you find it funny when people read classics that were controversial and iconoclastic decades ago and today can even be a bit boring, not original at all (doesn't mean they aren't important), but can't bring themselves to take a look at something more modern because it's... too controversial for them. I find it funny.
I am not at all sure that the classics, at least in literature, are so great. Much pulp fiction I've read seems to me to outclass some classics, which are very dull, and self-ingratiating. Generally I prefer pulp, though some books, eg, Sabatini's might be "pulp classics", and defy description. My old friend, maybe 70, said "aha! That book was rubbish at the time (1920s, 1820s,...say), and it is still rubbish." I completely agree with him.
@Peachey. You perfectly show my point. Thanks. The Cranberries* Zombie was their absolute worst, and if I wanted to be preached at, I would go to church, not listen to this song. Far better was the doop doop song. I hope it beat Zombie and reached no. 1?
*much Cranberries other stuff was good, admittedly. I was surprised at this abberation. Maybe it followed a bombing so was topical?