The writer refers to the snake as being more intelligent than all the animals. He is not suggesting that all snakes are more intelligent than other animals but that this being is not like the animals. In later scriptures this being is referred to as the adversary.
(Many English Bibles fail to translate certain words and instead transliterate them. "Satan" is one of these untranslated words. The Hebrew word means adversary and does not always refer to mankind's accuser.)
The adversary, in the form of a serpent, spoke to Eve and focused her mind upon the prohibition. “Has God indeed said, ‘You shall not eat of every tree of the garden’?”
Some questions are asked to instill doubt in the mind of the listener and I believe that this is what the adversary was seeking to accomplish in asking this question. God desires that his followers believe Him and trust His word and His assurances. The adversary convinced Eve to doubt God’s reliability.
There were many trees of which Adam and Eve could eat. The adversary emphasized this one negative, and thus distorted the situation. Eve's statement that they could eat of every tree except one tree. shows an understanding of the command.
God had said dying you shall die. Every day, small parts of our bodies die. The reason that frailty comes with age is because our bodies are slowly dying. As God said “Dying you shall die.” As long as they had access to the tree that provided life, their bodies were not decaying.
The adversary contradicted the statement which God had made and suggested that God did not want Eve to be like unto God. The basic appeal of humanism is to cause people to desire to be their own gods. Thus, they are deceived just as Eve was here.
Eve was tempted in the very same ways that we are tempted. She saw that the tree was good for food - the craving of the flesh. She saw that it was Pleasant to the sight -- the craving of the eyes. And she saw that it was desirable to make one wise - the pride of life.
Our relationship to God is based on His reliability and trustworthiness. Because God is all powerful, He can do all that He promises and because what He says is always true, we can have faith in Him.
Because Eve doubted God and the word of God, she sinned. “She took of its fruit and ate.” Not satisfied with this, “She also gave to her husband with her, and he ate.”
They disobeyed God and did exactly what he had told them not to do.