a) Why human have different skin colours?
We are all created in the image and likeness of God for the purpose of seeking him and glorifying him. (Genesis 1:26–27) .At the tower of Babel, God separated mankind across the earth, changing their languages and created different races.
From one man he made every nation of men that they should inhabit the whole earth; and he determined the times set for them and the exact places where they should live. God did this so that men would seek him and perhaps reach out for him and find him, though he is not far from each one of us. Acts 17:27. We are one in Christ Jesus and he does not show favoritism. (Galatians 3:28, Romans 2:11)
b) Has anyone ever seen God?
The scriptures say:When Abram was ninety-nine years old, the LORD appeared to him and said, "I am God Almighty; walk before me and be blameless. Genesis 17:1
The LORD appeared to Abraham near the great trees of Mamre while he was sitting at the entrance to his tent in the heat of the day. Genesis 18:1
“He said, "Hear now My words: If there is a prophet among you, I, the LORD, shall make Myself known to him in a vision. I shall speak with him in a dream."Not so, with My servant Moses, He is faithful in all My household; With him I speak mouth to mouth, Even openly, and not in dark sayings, And he beholds the form of the LORD. Why then were you not afraid To speak against My servant, against Moses?” Numbers 12:6–8
“Then Moses went up with Aaron, Nadab and Abihu, and seventy of the elders of Israel, and they saw the God of Israel; and under His feet there appeared to be a pavement of sapphire, as clear as the sky itself. 11Yet He did not stretch out His hand against the nobles of the sons of Israel; and they saw God, and they ate and drank.” Exodus 24:9–11
God spoke further to Moses and said to him, "I am the LORD; and I appeared to Abraham, Isaac, and Jacob, as God Almighty, but by My name, LORD, I did not make Myself known to them.” Exodus 6:2–3
I saw the Lord sitting on his throne, and all the host of heaven standing by him on his right hand and on his left. 1 Kings 22:19
The Lord talked with you face to face in the mount out of the midst of the fire. Deuteronomy 5:4
John 1:1 says that “the Word was God.” John 1:14 says that “And the Word was made flesh, and dwelt among us” Jesus said:I and my Father are one. John 10:30