What is proof that Shakespeare meant Lady Macbeth to be multifaceted character in Macbeth?
The one central aspect that proves beyond doubt that Lady Macbeth as a character is multifaceted is the way that Shakespeare moves beyond presenting her merely as a woman who gives herself totally over to evil and ambition and introduces the way that she is all too-human, even though this is something that she does everything she can to hide and to ignore, even herself. Consider how this is introduced in Act II scene 2 whilst she anxiously waits for her husband to kill Duncan:
Alack, I am afraid they have awaked,
And 'tis not done. The attempt and not the deed
Confounds us. Hark! I laid their daggers ready;
He could not miss 'em. Had he not resembled
My father as he slept, I had done't.
The reference to this one key faltering on Lady Macbeth's part speaks of a glint of humanity that adds interest and roundness to her otherwise resolute and thoroughly determined character. We would never have guessed that she would falter at such a key moment, given her earlier speeches in Act I in the play. It is also used to foreshadow her eventual emotional collapse and death at the end of the play.
It reveals a compassionate and humane side of Lady Macbeth. She is not as ruthless as she made out to be.
Lady Macbeth, in a way, descends from her masculine figure to become a loving daughter who is far too meek to give way to her ambitions and conduct such a cruel act.