_How did Jesus come into existence?_
Why did Jesus come to Earth?
Unlike other human beings, Jesus was a spirit in heaven before he was born on earth (John 8:23). It was Jehovah's first creation and helped him create all things. The Bible calls him the "only begotten" Son of God because he was the only one directly created by him (John 1:14). He is also known as "the Word", for he was the spokesman for his Father. (Read Proverbs 8:22, 23, 30 and Colossians 1:15, 16.
God sent his Son to Earth. To this end, he transferred his life to the womb of Mary, a young Jewish virgin. So, Jesus did not have a human father (Luke 1:30-35). He came to earth with three objectives: 1) to teach the truth about God, 2) to teach us by his example to do God's will, even in the face of difficulties, and 3) to give his perfect life as a "ransom". (Read Matthew 20:28.)
With the authority that God has given him, this mighty King will soon put an end to the evil people and the suffering they are causing. All who have faith in Jesus and obey Him will live happily on earth, which will become a paradise. (Read Psalm 37:9-11.)
https://www.jw.org/en/bible-teachings/questions/about-jesus/