Are you a Man?

The question of man's connection/disconnect to animal is brought up yet again in shakespeare. Multiple passages describe events, sensations, and characters to be animal like, and some are even called animals themselves.
In the beginning of Act III when Macbeth speaks to the murdererss, the first one says, "We are men, my liege," to which Macbeth responds,"Ay, in the catalogue ye go for men,/As hounds and greyhounds, mongrels, spaniels, curs,/ shounghs, water-rugs, and demi-wolves are clept" (3.1.92-5).
Conflict is also referred to by another name, in Act III scene II Macbeth refers to the conflict or issue of his kingship as a snake, saying that they have merely maimed it, not killed it, and problems may arise from her "former tooth" (3.2.15-8).
Macbeth refers to Banquo as "the grown serpent"(3.4.29) after having had him murdered.
Lady Macbeth, in her incesant lust for power, doubts her husband's ability to follow through and she repeatedly questions his manhood, wishing herself to have such power that a man is alloted. She asks him, "are you a man?" (3.4.56) when he sees Duncan's ghost and crumbles under guilt and pressure. Composing himself, he says, "I am man again" (3.4.108).
I think that Shakespeare's use of beast imagery plays on the time period- the darkness of a midieval castle, and perhaps the corresponding darkness of the people. The play is wrought with murder and betrayl, and what better place than the cold, dampness of stone walls amidst cold blooded murder?

Question: Do we sympathize with Macbeth? Is he merely a cuckhold? Does he want the power that badly?