Can a person find salvation all by themselves?
No, a person rarely finds salvation all by themselves. God ordained from the beginning of the human race that He would use human beings to promote His salvation, whether in the Old Testament or the New. Normally, someone must hear and understand the Word through another person's proclamation.
Les explains that God has always arranged for the Word of God to be promoted by humans, not angels. He notes that very seldom has he run across someone who found salvation all by themselves without the benefit of another human being. Paul writes in 2 Corinthians 5 that every believer is expected to be a minister of reconciliation and an ambassador for Christ, sharing what they know with those who have never heard or understood. The verses ask how people can hear without a preacher or proclaimer, and how anyone can preach unless they are sent.