At one point in the story, Macbeth decides not to murder King Duncan. He mentions that King Duncan has recently honored him and that they should proceed no further in the business of killing King Duncan:
We will proceed no further in this business.
He has recently honored me, and I now have the
Golden opinions from all sorts of people,
Which I want to enjoy for a bit longer, and
Not cast them aside so soon.
Truly, Macbeth is human and he has changed his mind. He realizes that King Duncan has honored him. He realizes how wrong it is to proceed to murder someone who has recently honored him.
Then Lady Macbeth insults Macbeth's manhood. She asks him if he is afraid. She manipulates Macbeth and finally convinces him to proceed with murdering King Duncan:
Are you afraid
To be the same man in reality
As the one you wish to be? Would you have the crown
Which you believe to be the ornament of life,
And yet live like a coward in your own self-esteem,
Macbeth finally gives in and agrees to murder King Duncan, calling it a terrible event:
I’m convinced, and I commit
Every part of my body to this terrible event.
Let’s go and pass the time by pretending to be happy.
False faces must hide what the false heart knows.
From this statement, it is clear that Macbeth is human. He calls the event of murdering King Duncan a terrible event. Likewise, he states that that they must "pretend" to be happy. Clearly, he is troubled by thoughts of murdering King Duncan. This proves his human side. In fact, Macbeth would have not murdered King Duncan if Lady Macbeth had not challenged his manhood. She was very convincing.