God gave Moses three signs at which he would show Pharaoh that Moses was the chosen on. Signs that not only Pharaoh, but people living on the earth need to take heed and listen to. These signs were to provide proof that Jehovah is really the one speaking through Moses, and that Moses is carrying out God's will.
The first sign was the staff turning into a serpent. The staff is a representation of all that we rely on apart from God. The staff is the devil in disguise trying to usurp us into not relying on our God, but of our own strengths and abilities. The staff turning into the serpent is to show the devil hiding in these things we hold on to so dearly. If we aren't taking the snake by the tail and are using our "staff" for any other purpose other than God's will and authority, then we are being used by the devil. That was the first sign to be revealed.
God is God. There is no other, the God of Abraham, Isaac, and Jacob are all one God, Jehovah. He has shown Himself to Moses, and has given three signs to prove that He is who He is. The first was the staff, the second was the leprous hand; The hand becoming leprous.
Exodus 4:5 That they may believe that Jehovah, the God of their fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has appeared to you.