The Toledoth's of Genesis are not allegory, but historical narrative. Adam and Eve are two real persons/beings, created by God, approximately 6,249 (as of AD 2024) years ago -
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The Bible, from Genesis to Revelation, as well as each writer, understands Genesis in the historical (not allegorical) narrative. Paul even explains that the natural is first, then follows the spiritual understanding (1 Cor. 15:46). This is even explained as such, not only by most Christians throughout history -
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It is not possible "that God placed humans throughout the world and that the story of the garden is a parable", for it would violently wrest (Psa. 56;5; 2 Pet. 3:16) not only the context itself, but also the contexts of all the other writers/speakers on the subject, in scripture. There would be no need for a singular new man (Adam - Jesus; 1 Cor. 15:47), if there were not the original singular first man Adam. They are linked in type and antitype, among other things.
Colouration is simply genetic variation built into the original Adam, from the beginning that is affected by various conditions, such as diet, locale, population, other pressures which affect melatonin levels, and other factors. So, yes, we are to understand that "white, black, Indian & Asians" are all descendants of one singular pair of persons/beings (Adam & Eve). Evolutionism is the myth.
Gen_3:20 And Adam called his wife's name Eve; because she was the mother of all living.
Act_17:26 And hath made of one blood all nations of men for to dwell on all the face of the earth, and hath determined the times before appointed, and the bounds of their habitation;
We are all related to the singular - Adam, as well as to Noah (bottleneck of the global flood).
Creation documentation -
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Adam & Eve, in their existence and marriage represent the JEHOVAH Elohiym, or the eternal heavenly Trio, of the Father, the Son and the Holy Ghost/Spirit. Adam, as Head of mankind, represents the Father. Eve, from the side of Adam, represents the Son who is always submitted to the will of His Father by love, and is of the nature of the Father, and their love is bound together by God, who is represented by the Holy Ghost/Spirit between them. If, the beginning is a myth, or allegory, this is all destroyed, and the perfect image and likness of JEHOVAH Elohiym is distorted into myth/allegory as well.
Allegorizing Genesis, vaporizes, not only the rest of history into the same, for where will one draw the line?, it also vaporizes the need of the Gospel, Salvation, Redemption, for what need would there be of those things, based upon the myth/allegory of that which is not in fact actual:
Gen 3:15 And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel.
Gen 3:21 Unto Adam also and to his wife did the LORD God make coats of skins, and clothed them.