On my first character, whom I named Localdefence on the Lightbringer server (you can look him up, he's a level 41 tauren, but I lost the account he was on to hackers), I didn't think you could gain experience by questing so I literally ONLY leveled up by killing mobs.
Also, I started playing in Vanilla, and it wasn't until WotLK that someone (my sister) told me that stats are more important than armor.
And I remember being in Bloodhoof Village and seeing a level 60 on a mount, thinking he was the most uber player in WoW and being amazed that I saw someone such a high level.
I remember walking everywhere and acting like reaching level 40 was a huge celebration because I could finally get a mount.
i use to have a lot of trouble distinguishing between players and npcs when i first started :P
i spoke to a guard in teldrassil on my first character and didn't know how i did it, i then spent about 15mins trying to open the dialogue window with another guard, turns out it wasn't a guard, it was another play :P my friend was telling me to right click, and i was, but nothing was happening :P he had to bring his dwarf all the way from the dwarf ironforge to come help me, and it was just some afk player in the starting area
i also did the opposite quite a lot and thought random npcs were players, like npcs that are out in the world, or fighting mobs.
my first mmo and i was like 12, dont judge :P
i also was the biggest huntard ever, i remember being in razerfen downs with dual wield daggers meleeing stuff. i did that a lot :P i also got to around level 30 without using talent points, i had no idea i had them until a friend explained to me.