Originating in Barcelona in the 1400s to tell biblical stories to the illiterate populace. They are characters that take part in parades and are around 10 feet tall, with large paper mache heads. They all have names for example, Mustafa is a moor head.
The informant and his family also went to a festival featuring these giants during a visit to Spain earlier this year; these characters are apparently not specific to any one festival, and instead appear in some of many throughout the year.
Context: The informant is in his 50s; he grew up in Barcelona, Spain (where he went to these parades), immigrated to the U.S. as a young adult, and started a family in San Diego, CA where he lives today.
Interpretation: This character seems to be one that celebrates Spanish culture in general, and is not specific to any holiday in particular – however, they are associated with festivals in Spain and are sometimes represented in parades. My guess is that, by virtue of existing in Spanish folklore for such a long time, it has become more symbolic of Spanish culture (as distinct from outside cultures) than of the particular biblical stories it initially represented.