Frank Thomas and Ollie Johnston identified the individuals caricatured in their book Too Funny for Words: Disney's Greatest Sight Gags. In order of appearance:
First came the banderilleros, as represented by Ham Luske, Jack Campbell, Fred Moore and Art Babbitt.
They were followed by three picadores, the last of which is a caricature of Bill Tytla.
Finally, the matador arrives, followed by his moza de espada, in the guise of Ward Kimball.
Of the sequence,Thomas and Johnston noted:
"The parade of participants for the great bullfight in Ferdinand the Bull (1938) was a series of caricatures of animators and directors, with the animator who conceived the whole idea bringing up the rear and leering knowingly at the camera. It was rumored that Walt thought the matador was a caricature of himself, but the animator quickly denied giving the character any resemblance to his boss."
That animator of course was Ward Kimball. And even in a later interview, Kimball made no acknowledgment of basing the matador on Walt: "I caricatured myself, Fred Moore, Ham Luske, Jack Campbell, Art Babbitt and Bill Tytla." Of his own animated incarnation, Kimball noted, "I came in with a pillow with a sword on it, and I think I liked the part."