Though I would argue that the Fire Shrine Keeper is a part of the Sun Empire/Dinosaur faction because it is quite clearly a man-made construct (not entirely elemental), but does not align with the colours, designs, materials, or elements of the Merfolk—the only other faction that would have been present in Ixalan long enough ago or creative/powerful enough to have left behind such magical guardians at the continent's [presumably abandoned] shines.
Though I would argue that the Fire Shrine Keeper is a part of the Sun Empire/Dinosaur faction because it is quite clearly a man-made construct (not entirely elemental), but does not align with the colours, designs, materials, or elements of the Merfolk—the only other faction that would have been present in Ixalan long enough ago or creative/powerful enough to have left behind such magical guardians at the continent's [presumably abandoned] shines.