Why did God create such complexity in man? During Creation, God created man:

Genesis 2:7 KJV


  And the LORD God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul. 


Why did God created such complexity - down to cellular level, with so many organs and fluid - into man? Wouldn't things be much simpler if we were created with less complexity - and probably with the chance of reducing all the medical problems that we face today.
He created such complexity because it exists in Him as well, as we are explicitly created after His own image and in His likeness, as His children.

Genesis 1:27 (KJV)


  27 So God created man in his own image, in the image of God created he him; male and female created he them.


As for medical problems, those are inherently bound up with death and mortality, which weren't part of the original creation, but were introduced in the Fall.