if Adam and Eve were the first people, why are there different races? Where did different races come from - Caucasian, Oriental, Semitic, etc.?
It actually comes closer to home than Adam and Eve. At the flood, only Noah and his three sons and their wives survived. What we construe as different ‘races’ are all descended from the three sons of Noah. The seperation into what would become nations began at Babel when God confounded the language.
Genesis 11:1 Now the whole earth had one language and one speech. 2 And it came to pass, as they journeyed from the east, that they found a plain in the land of Shinar, and they dwelt there. 3 Then they said to one another, "Come, let us make bricks and bake them thoroughly." They had brick for stone, and they had asphalt for mortar. 4 And they said, "Come, let us build ourselves a city, and a tower whose top is in the heavens; let us make a name for ourselves, lest we be scattered abroad over the face of the whole earth." 5 But the LORD came down to see the city and the tower which the sons of men had built. 6 And the LORD said, "Indeed the people are one and they all have one language, and this is what they begin to do; now nothing that they propose to do will be withheld from them. 7 "Come, let Us go down and there confuse their language, that they may not understand one another’s speech." 8 So the LORD scattered them abroad from there over the face of all the earth, and they ceased building the city. 9 Therefore its name is called Babel, because there the LORD confused the language of all the earth; and from there the LORD scattered them abroad over the face of all the earth.
This resulted initially in 70 families (which would become nations) which separated and spread through the world because they couldn’t understand one another.
Genesis 10:1 Now this is the genealogy of the sons of Noah: Shem, Ham, and Japheth. And sons were born to them after the flood. 2 The sons of Japheth were Gomer, Magog, Madai, Javan, Tubal, Meshech, and Tiras. 3 The sons of Gomer were Ashkenaz, Riphath, and Togarmah. 4 The sons of Javan were Elishah, Tarshish, Kittim, and Dodanim. 5 From these the coastland peoples of the Gentiles were separated into their lands, everyone according to his language, according to their families, into their nations. 6 The sons of Ham were Cush, Mizraim, Put, and Canaan. 7 The sons of Cush were Seba, Havilah, Sabtah, Raamah, and Sabtechah; and the sons of Raamah were Sheba and Dedan. 8 Cush begot Nimrod; he began to be a mighty one on the earth. 9 He was a mighty hunter before the LORD; therefore it is said, "Like Nimrod the mighty hunter before the LORD." 10 And the beginning of his kingdom was Babel, Erech, Accad, and Calneh, in the land of Shinar. 11 From that land he went to Assyria and built Nineveh, Rehoboth Ir, Calah, 12 and Resen between Nineveh and Calah (that is the principal city). 13 Mizraim begot Ludim, Anamim, Lehabim, Naphtuhim, 14 Pathrusim, and Casluhim (from whom came the Philistines and Caphtorim). 15 Canaan begot Sidon his firstborn, and Heth; 16 the Jebusite, the Amorite, and the Girgashite; 17 the Hivite, the Arkite, and the Sinite; 18 the Arvadite, the Zemarite, and the Hamathite. Afterward the families of the Canaanites were dispersed. 19 And the border of the Canaanites was from Sidon as you go toward Gerar, as far as Gaza; then as you go toward Sodom, Gomorrah, Admah, and Zeboiim, as far as Lasha. 20 These were the sons of Ham, according to their families, according to their languages, in their lands and in their nations. 21 And children were born also to Shem, the father of all the children of Eber, the brother of Japheth the elder. 22 The sons of Shem were Elam, Asshur, Arphaxad, Lud, and Aram. 23 The sons of Aram were Uz, Hul, Gether, and Mash. 24 Arphaxad begot Salah, and Salah begot Eber. 25 To Eber were born two sons: the name of one was Peleg, for in his days the earth was divided; and his brother’s name was Joktan. 26 Joktan begot Almodad, Sheleph, Hazarmaveth, Jerah, 27 Hadoram, Uzal, Diklah, 28 Obal, Abimael, Sheba, 29 Ophir, Havilah, and Jobab. All these were the sons of Joktan. 30 And their dwelling place was from Mesha as you go toward Sephar, the mountain of the east. 31 These were the sons of Shem, according to their families, according to their languages, in their lands, according to their nations. 32 These were the families of the sons of Noah, according to their generations, in their nations; and from these the nations were divided on the earth after the flood.
It is reasonable to suppose that the changes in physical appearance - skin colour etc. came as a result of marriage being restricted to those of their own nation-family and language which would have been quite small at the outset.
The scriptures which claim to be inspired by our creator speak of all peoples being descended from Adam and Eve and this is evidenced by the fact that they all die – a sentence which was passed upon Adam and his progeny because of disobedience.
Disobedience to God is called sin.
Ezekiel 18:4 Behold, all souls are Mine; The soul of the father As well as the soul of the son is Mine; The soul who sins shall die.
Paul tells the Athenians:
Acts 17:24 God, who made the world and everything in it, since He is Lord of heaven and earth, does not dwell in temples made with hands. 25 Nor is He worshiped with men’s hands, as though He needed anything, since He gives to all life, breath, and all things. 26 And He has made from one bloodevery nation of men to dwell on all the face of the earth, and has determined their preappointed times and the boundaries of their dwellings, 27 so that they should seek the Lord, in the hope that they might grope for Him and find Him, though He is not far from each one of us; 28 for in Him we live and move and have our being, as also some of your own poets have said, ‘For we are also His offspring.’ 29 Therefore, since we are the offspring of God, we ought not to think that the Divine Nature is like gold or silver or stone, something shaped by art and man’s devising. 30 Truly, these times of ignorance God overlooked, but now commands all men everywhere to repent, 31 because He has appointed a day on which He will judge the world in righteousness by the Man whom He has ordained. He has given assurance of this to all by raising Him from the dead.
God’s offer of salvation from death is open to all men and women regardless of their ‘race’ if they will believe and obey the Gospel preached by Jesus Christ and his apostles.
Mark 16:15 And He (Jesus) said to them, "Go into all the world and preach the gospel to every creature. 16 He who believes and is baptized will be saved; but he who does not believe will be condemned.
Acts 10:34 ...in truth I perceive that God shows no partiality. 35 But in every nation whoever fears Him and works righteousness is accepted by Him. 36 The word which God sent to the children of Israel, preaching peace through Jesus Christ—He is Lord of all— 37 that word you know, which was proclaimed throughout all Judea, and began from Galilee after the baptism which John preached: 38 how God anointed Jesus of Nazareth with the Holy Spirit and with power, who went about doing good and healing all who were oppressed by the devil, for God was with Him. 39 And we are witnesses of all things which He did both in the land of the Jews and in Jerusalem, whom they killed by hanging on a tree. 40 Him God raised up on the third day, and showed Him openly, 41 not to all the people, but to witnesses chosen before by God, even to us who ate and drank with Him after He arose from the dead. 42 And He commanded us to preach to the people, and to testify that it is He who was ordained by God to be Judge of the living and the dead. 43 To Him all the prophets witness that, through His name, whoever believes in Him will receive remission of sins.
Our nationality makes no difference to God.
I hope you find this helpful.