The above sounds like a stage in an ongoing project.“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.” KJV
replenish = fill (in this case - the earth) up again. To restore (a stock or supply) to a former level or condition.
[This implies that humans once used to be plentiful and something happened which diminished the Human stock.]
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Re Genesis 1:28
QFB: After this is accomplished, what then?