Did Constantine Start The Catholic Church?

Many Christians believe that the Roman Catholic Church was started by Emperor Constantine.

 that the early church operated the way their church operates today.

With beliefs such as scripture alone, faith alone, once saved always saved, etc.

Now I have videos refuting all these doctrinal errors on my channel.

Please see those videos for further examination of those topics.

They believe that all the uniquely Catholic doctrines were added either by constantine or sometime later, 

Doctrines such as papal infallibility, bishops, confessing sins to a priest, praying to Mary and other saints, purgatory, infant baptism etc…

and that the true church was driven underground.

Is this true?