I think the church doesn’t like to acknowledge the very real and volume of documentation of Jesus Christ the man for 2 reasons
1) they think it takes away from the divinity of Christ to emphasize he was a historical person
2) the early followers of Christ were rebellious and uncontrollable and that is always on the verge of happening ever since. If you follow Christ before your government or your church you’d consider yourself outside all their earthly influence and requirements of you. That Christ was historical is outside their narrative where they have to interpret Him for you and intercede with Him on your behalf.