Churchs were mad that nuns were giving away too much money to the poor, so they made a rule to try to reduce it. a bunch of nuns started giving away a bunch of stuff to celebrate st Nicholas Day to get around the rules. Protestants show up and want to get away from celebrating saints, people like giving and receiving stuff on st Nicholas Day, so Protestants come up with wanting baby Jesus giving the gifts, but babys aren't very good at following directions so they get older kids to do it which is where Chris Kringle comes from. You end up with a bunch of regional offshoots of either st Nicholas or of Chris Kringle. Then the idea of putting bad kids in sacks and beating them with sticks shows up but for some reason no one wanted st Nicholas or a baby Jesus analog to do the beating so a bunch of offshoot characters start showing up as helpers to the gift giver to punish bad kids.
The krampus is hard to pin down because it was in rural areas of Germany and most of the documentation about it is from post cards made in cities using 2nd and 3rd hand information to design what the krampus looks like.