Question: "Why did God sometimes change a person's name in the Bible?"
Answer: When God changed a person’s name and gave him a new name, it was usually to establish a new identity. God changed Abram’s "high father" name to “Abraham,” "father of a multitude" (Genesis 17:5) and his wife’s name from “Sarai,” “my princess,” to “Sarah,” “mother of nations” (Genesis 17:15). We know from history that the descendants of Abraham and Sarah formed many nations, including the Jews’ and Muslims’.
God changed Jacob’s "supplanter" name to “Israel,” “having power with God” (Genesis 32:28). He changed Simon’s "God has heard" name to “Peter,” "rock" (John 1:42). Why did Jesus occasionally call Peter “Simon” after He had changed His name to “Peter”? Probably because Simon sometimes acted like his old self instead of the rock God called him to be. The same is true for Jacob. God continued to call him “Jacob” to remind him of his past and to remind him to depend on God’s strength.
Why did God choose new names for some people? The Bible doesn’t give us His reasons, but perhaps it was to let them know they were destined for a new mission in life. The new name was a way to let them in on the divine plan and also to assure them that God’s plan would be fulfilled in them.