not wikipedia definitions but maybe not so false either:

humor: some kind of verbal "sliding" from reality to unreality that is an attempt to be funny i.e to provoke smile or laugh.

pun: some kind of "sliding" in the meaning of a word or a group of word based on their phonetic proximity that is not necessary attempted to be funny.

consequences:
=>As it has some something common with the essence(to be a "sliding"), The Pun may be a good way to acceeds to what is the essence of humor. and so can't be the lowest form of humor.
=>Nethertheless the Pun as foundation of all humor is probably too restrictive. As there are others proper forms of humor that are not based on phonetic proximity
It seems to me that foundation of humor is a larger language "sliding" that is based on phonetic proximity or proximity of meaning.

PS: I'm not sure sliding is very appropriate in that use... transition? "glitch"?...

MG!!! The most infamous member these forums have ever got!