It is written, "For precept must be upon precept, precept upon precept; line upon line, line upon line; here a little, and there a little: (Isaiah 28:10ff)";And?
The long held belief that GOD ONLY used 2 originally sinless people to begin populating the entire earth, DOES NOT stand up to "sound" doctrinal scrutiny when soundly, carefully and reasonably examined (for example, who are those that Cain is worried about, after murdering his brother Abel, when he says, ". . . I shall be a fugitive and a vagabond in the earth; and it shall come to pass, that every one that findeth me shall slay me" in Genesis 4:14, if there is ONLY Adam, Eve, & Cain populating the earth at that time???); and is shown to be very doubtful &/or questionable as can be, especially when one considers, AMONG SO MANY OTHER infallible proofs, how HE (GOD) seems to have had to use 6 SIN TAINTED people (Noah's 3 sons & their 3 wives) to begin RE-populating the entire earth after the Flood.