***Once again, you are misrepresenting the beliefs of members of churches of Christ. We do not follow Alexander Campbell, we follow Christ. ***
Then from the time of the Apostles, was there anyone saved before Campbell, Stone and Walter Scott came along? About the only people immersing were Baptists and it was "to follow Christ". Every one else sprinkled.
Those who follow the teachings of Scripture and believed the Word of God, repented of their sins, confessed that Christ was the Son of God, and were baptized for the remission of their sins are saved.
Also, since you have no way of knowing how everyone in history has believed, then you have no way of knowing who did and did not immerse throughout history.