Who were the first people on earth besides Adam and Eve?
There were no other people besides Adam and Eve.
Adam named his wife Eve because she was the mother of all living. Genesis 3:20
Adam and Eve disobeyed God and ate of the fruit of the tree of the knowledge of good and evil, bringing sin and death upon themselves and their descendants. After their sin they were expelled from Eden and barred from the tree of life. This is the reason that we are all mortal. Had there been other people besides Adam and Eve, they would not have been subject to death, would have had access to the tree of life and still be alive today.
God provided a redeemer Jesus Christ, a descendant of Adam through his mother, to provide a way of escape from death for those who will believe and obey the Gospel he preached. Those, along with the faithful of old, who believed God's promise of a redeemer and lived accordingly, will be raised from the dead to eternal life when Christ returns. 1 Corinthians 15:22
To be 'in Christ' we must:
I hope this helps,