Giants and cabezudos or big heads are a usual part of many festivities in West Europe -an also, to some extent, in Latin America. Groups of children taunt cabezudos, and they chase them by the streets...I remember that from my childhood. Cabezudos can give you a head-butt, so you
run as fast as possible. It was very fun.
I saw them in Santiago, the 25th July, many years ago (see photo).
Giants tend to represent characters associated with local history, but generally a king, a queen, and a "Moor", are always present (I remember, in a Basque village, a "Mexican charro", because it was formerly a migrant town).
Today, it is a kind of much liked tradition, and they are financed by city halls.
I read somewhere a theory about that those giants were initially present in Corpus Christi, and they represented the kings or parts of the world, giving homage to Christ. Beside giants and cabezudos, in Corpus there were "tarascas", a kind of monster or serpent.