Don't be too quick to label things as biased, ignorant, or arrogant. Inferring blanket labels ascribes a certain arrogance to your viewpoint.
It was arrogance to label anything but human as 'lower life forms'. And if my statement is arrogant, in that I'm stating that one cannot understand an animal because one is comparing to a human, then so be it. We cannot understand anything but a human stand point. And even then, it isn't 100%. Hence it is a bias standpoint. And notice, I didn't stat any such term in opposition towards anyone in this conversation.
In the case of horses, bulls, and mechaniloids... they have a level of awareness in that they act from instinct, prior experience/programming, and exhibit consistent social behavior. But mechaniloids have not been observed to act completely contrary to instinct/programming/social behavior with no outside external forces acting on them. This apparently is what separates mechaniloids from X (Zero, and reploids) and Dr. Light basically said as much.
Machaniloids have not been 'shown' or given the 'on stage' chance to be allowed to show such. All we see, is a Mechaniloid 'under enemy influence' (from hunter stand point). Not a mechaniloid in it's prime function. So we cannot assume either way. Now, if it was within more of an OVA, other than 1 occurrence within Day of Sigma, then we can speculate more accurately. Since then we would have more insight. But benefit of the doubt must be issued to speculate such.
What you, I, and Zan are slipping on here in this discussion is a lack of definition of terms. For instance, how does one define "Soul"? How does one define "Self-Awareness"? How does one define "Intelligence"? Are these all synonyms? I for one, don't think so.
How does one assume humans have a 'Soul'? How does one assume humans don't have a 'Soul'. How do we assume any other form of life on this planet has either/or? Life is a natural bias standpoint. Since in life, we know nothing of death. And such, when death occurs, we cannot return and share the experience. When alive, everything knows life. When dead, everything experiences such and continues... Soul, Self-Awareness, intelligence... All one sided to what Life can teach, and for humans to at least interpret...