We humans seem to display a significant cognitive bias while thinking about intelligence. ;)
Does intelligence admit a partial order? I have often thought about this question and I find that the concept of intelligence and it's partial order are highly suspect and probably the output of cognitive biases.
On the bottom of the ocean floor, is the human more intelligent or is the octopus? Is the HIV more intelligent or the common cold virus and are we more intelligent then them? We are? From our perspective or the viri's? Or from some universal perspective? Is the neuron in optical lobe more intelligent or the one in your spinal cord?
Intelligence is very likely a wrong concept. It is a popular concept but likely the wrong one. I mean wrong in the sense that it is likely a purely cognitive myth. Humans consider whatever they perceive of as better than them in the medium to long time periods as more intelligent. And they tend to apply the same concept extrapolatively backwards too as in a bee or a beaver would have to think of us as better. The fact that concept breaks down when trying to apply it to non human like things and activities is ample evidence.