The original Rolemaster probably ignored a few key class tropes in their original work. Paladins comes to mind of course, but in my mind one of the most important is the Shaman!
If Clerics/Priests are defined as members of an organized religion, than perhaps we can define a Shaman as a leader of a decentralized or non-organized religion. Maybe the society or group worships a local god, or a real god under an avatistic identity, but the belief system lacks the more coherent structure and trappings of an organized religious institution. If you are gaming in a “classic” fantasy setting, you’ll probably have, or encounter a variety of primitive societies: Orcs, Goblins, barbaric tribes etc. These groups will most definitely have a version of a “Cleric”, but different than the type found in Rolemaster that casts Absolutions and Channels.