Groosch!?!?!!
How kud I have missed this!?!?!???
Sawrey....fer nert gitt'in teu yer sooner!
Well...teu answer thr question....I'd point yer teu these passages on the company's page Dan cited....
A: Goofy is a dog! Good-natured but not that bright
Uhyuck!
While I must protest the first part of this statement,
thar's knoe debat'in the latter half!
Goofy was created as a human character, as opposed to Pluto, who was a pet, so he walked upright and had a speaking voice.
In conversations over thar yar's with my great uncle Dave Smith (Disney company archivist) I've come teu the underderrstand'in
that Walt's (Dad's) {blush} intent was to most likely to create a careactor whose audience could really relate to on a personally level....a careacter who was symbolic of "the common man".
(no offense guys!)
But thur my mishaps and adventures, and as the 'ultimate proof' of murphy' law (in most instance - except when Donald loses his temper) folks could/can see a part of themselves.
In consideration of the simple complexity of...well...of my careactor, and as illustrated by the second quote above ..... I chose to believe that the answer is a human careactor.
This is supported by the adaptability the careacter has had...drives cars, flys planes, plays hockey, fishes etc.etc.etc.
And yet while experiencing all that can go wrong...the affability underscores the wonderment with life's simplier tasks and pleasures that anyone's in law or buddy could share.
If this helps yer....dernt send me a bone....
Not to mention a huge sweetheart. 
