The beasts have a very large range, their types. sizes, origins, constructions and characters are legion.
However, the ones we are concerned with are there to support the dancers and add colour and humour to the displays.
Much has been written about their origins and the link below leads to a learned treatise on the early history of the Hobby-horse, dating from the first records in the seventh century, some 1400 years ago. Quite a pedigree!