In some of Carlos Huante's concept art, he had a being that is clearly an Engineer, yet whose head shape more resembles that of a Neanderthal:
Now personally, I think that it would be fascinating to develop the idea of different species of Engineers, similar to how modern humans once shared the Earth with neanderthals, denisovans, homo floresiensis, "Black Neanderthals," and possibly a few other races. These other creatures might not necessarily be more primitive overall than the standard Engineers, just with different abilities and mental capacities (neanderthals had much better eyesight while it took denisovan genes to allow homo sapiens to live in the Himalayas). Anyone else like this idea?