I've been playing Halo 5 for a little bit and I've opened quite a few packs but, I have gotten nothing out of them. Do you only get visors and armor by leveling up?
To quote this page on the wiki:
Armor permutations in Halo 5: Guardians allow players to customize their Spartan player model. These armor sets can be obtained by getting to a certain rank in the game along with unlocking achievements in Halo: The Master Chief Collection and obtaining armor in REQ packs.
So it sounds like you can get armor in Halo 5: Guardians in those three ways.