If you have watched a few Minecraft content creators, you'll understand what the origins are about. But if not then it's pretty much a mod that some mod developers created that a few Minecraft content creators have played on. Basically you can any origin that will give you specific abilities that will enhance your gameplay by either picking a merlin that allows you to breath underneath water, but having the default of struggling to gather materials on land because you can't breath on land like you do with your water. Whilst a chicken or Elytrians will be flightless with slow falling like the chicken or will be given Elytrians wings already and have the ability to shoot of into the sky as well as a panic button to shoot you up one more time before flying down eventually to the ground, not to mention the default is that you become weak if under any blocks for a certain amount time. So enjoy the future stories involving the mod as a functional storyline experience.