But there were still adjustments, most importantly Christianity, which needed a few good miracles to demonstrate authority (note Jesus only heals people in order to demonstrate his divine mandate, not just to, well, heal people.)

That depends on the Gospel in question. The Johannine Jesus works miracles to show that he's God; the Matthean Jesus is constantly frustrated that everyone follows him around, tells everyone to shut up, and rejects Satan's temptation to publicly show his divine favor as an affront to God.