Platforming should be the earliest known type of level in Everybody Edits. It lets players do a platformer level within the general level. This is the type of room that most commonly keeps players.
Minigames levels are mini-platforming levels. Editors usually get creativity constrains, unless they repeat a level.
Racing levels probably appeared only after keys and locks came out. A winner is chosen by being the first player who gets past the level. He triggers a switch, and all the other players fall down and go back to the start of the level. This type of level can get extremely frustrating if you are a newbie, as more players will stream into the room and prevent you from winning. However some people still stay for quite a long time, maybe because they know that they can get past a level as long as others do it. Most racing levels do have safespots, usually of the same colour to prevent people from ragequitting.
Stair levels are repetitive levels that use the shape of stairs (blocks put diagonally to mimic stairs) to make a racing level. It is the perfect newbie level as there are usually safespots.
Themed levels usually have one and only one theme repeated throughout the entire level. For example, if a level is named Baconland, it might have a theme of bacon (Creator: NIH). Some levels have a theme not clear at first. For example, a level named Bears in Space, with lines all over it as if it had been griefed, does not look like it is a level at all. But, in fact, if you can platform around the lines, then the theme is actually about griefers.