Seraphim, etc.

...the symbolic system pertaining to personal piety reveals perceived needs for protection in a more general sense, as represented by the various motifs of protective spirits and apotropaic monsters. An interesting phenomenon that again reflects the coincidence of the symbolic systems of official and personal religion is the frequent presence of winged Uraei in Israelite iconography. Particularly in Judean iconography, this stands in stark contrast to the very few occurrences on other West Semitic seals (table 5.16). The winged Uraei, which have generally been associated with biblical seraphim, along with the sphinxes, who were in turn associated with cherubim, may together be considered protective lower deities who would have been of some importance for personal piety and possibly also as mediators of YHWH. The popularity of the seraphim in particular reveals that elements of the official symbolic system, especially aspects of an apotropaic or protective nature, were eminently able to be assimilated in realms of personal piety.—Family and Household Religion in Ancient Israel and the Levant, page 385