Them refers only to Adam and Eve, not to some random other people.  Genesis 1 is a summary of God's entire creation.  Genesis 2 is the details of how He created the first man and the first woman.  They aren't a sequence.  They are Him going into more details about His special creation of mankind, which was the purpose of His whole creation.

"12Therefore, just as through one man sin entered into the world, and death through sin, and so death spread to all men, because all sinned— " (Romans 5:12).  The first sin was committed by Eve and then Adam.  Sin led to death.  Therefore there was no death before Adam and Eve, so there can not be people before Adam and Eve.  God tells exactly how He created Adam and Eve.  They did not come from other people or animals.

"So also it is written, “The first man, Adam, became a living soul.” The last Adam became a life-giving spirit. " (1 Corinthians 15:45)  This verse explicitly says Adam was the first living soul.

"But from the beginning of creation, God made them male and female.  For this reason a man shall leave his father and mother, and the two shall become one flesh; so they are no longer two, but one flesh." (Mark 10-6-8)  This New Testament verse not only talks about man and woman being created "from the beginning of creation", but also quotes Genesis 2:24 as fact.