It seems to me that if one is going to claim that animals' actions only
appear conscious because of humans applying heuristics, and that in reality animals are merely exhibiting complex non-conscious behavior, then there is no reason one should not consider that possibility of other human beings as well, or perhaps even one's self. Taken to its logical conclusion, one could claim that nothing is really conscious and it is all an illusion.
On the other hand, if we recognize that the behaviors we witness in other animals can be explained as complex responses to stimuli, and accept that our own behavior can be similarly explained, but never the less also recognize that our own experience of being is real, that there is something here, then I think we are forced to consider that whatever that quality is it also exists in other beings.
And if that quality exists in other human beings, because they are like us, then how much like us must they be? If mammals display similar behaviors to us then is it not reasonable to infer that they also have this quality? And if even some lizards, say, exhibit a few of these qualities, do they not also potentially posses it? And if we accept that even things very different from us can experience reality in this way, then how unreasonable is it, really, to say that everything does?