Genesis 1:28 -- And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth.
God says to replenish the earth. How can you replenish something that has not been lost? Does this mean that there was an earth here before Adam and Eve? I wonder what happened and what was here before Adam and Eve or any of the animals?
The following are my personal opinions which I have tried carefully to base of scripture. I do not claim to be 100% correct nor do I disrespect anyone else's ideas.
The ideas of a pre Adamic race are generally believed to have started with Roman Emperor Julian the Apostate around 363 AD although some credit this theory to a Mr. Isaac La Peyrère 1655.
As far as replenish it is generally considered a mistranslation. I compared (not counting any King James) 24 translations and 19 disagreed with that translation and only 5 concurred.
When you take in account the King James translations I compared 5 used replenish but the Modern King James and King James 2000 did not so there is disagreement on this translation but the majority of bible translators disagree with replenish by about 4 to 1 over replenish which is more commonly translated "fill".
The New Testament scripture declares that Adam was indeed the first man:
1Co 15:45 And so it is written, The first man Adam was made a living soul; the last Adam was made a quickening spirit.
TheG3588 firstG4413 manG444 AdamG76
first-
G4413
πρῶτος
prōtos
pro'-tos
Contracted superlative of G4253; foremost (in time, place, order or importance): - before, beginning, best, chief (-est), first (of all), former.
man-
G444
ἄνθρωπος
anthrōpos
anth'-ro-pos
From G435 and ὤψ ōps (the countenance; from G3700); manfaced, that is, a human being: - certain, man.
Adam-
G76
Ἀδάμ
Adam
ad-am'
Of Hebrew origin [H121]; Adam, the first man; typically (of Jesus) man (as his representative): - Adam.
Gen 2:5 And every plant of the field before it was in the earth, and every herb of the field before it grew: for the LORD God had not caused it to rain upon the earth, and there was not a man to till the ground.
Gen 2:6 But there went up a mist from the earth, and watered the whole face of the ground.
Gen 2:7 And the LORD God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul.
Gen 2:8 And the LORD God planted a garden eastward in Eden; and there he put the man whom he had formed.
There was not a man to cultivate before Adam.
Neither was there any compatible mate for Adam:
Gen 2:18 And the LORD God said, It is not good that the man should be alone; I will make him an help meet for him.
Gen 2:19 And out of the ground the LORD God formed every beast of the field, and every fowl of the air; and brought them unto Adam to see what he would call them: and whatsoever Adam called every living creature, that was the name thereof.
Gen 2:20 And Adam gave names to all cattle, and to the fowl of the air, and to every beast of the field; but for Adam there was not found an help meet for him.
Eve was so named because she was the mother of all living.
Gen 3:20 And Adam called his wife's name Eve; because she was the mother of all living.
It seems that Adam was 130 years old at the time of Cain's fearful departure. Adam and Eve had plenty of time to raise a multi generational family so it would not really be hard to find a suitable spouse.
Cain lived some 900 plus years so he had plenty of time to establish a community.