All of those existed back when Rangers were first made.
Ranger first appeared in The Strategic Review volume 1, number 2, published in Summer 1975. The only older classes are Fighting Man, Cleric, Magic User, Thief, and Paladin. And it's only a month or two newer than Thief and Paladin from Supplement I: Greyhawk.
The issue is that WOTC got imaginative after the PHB. When they were force due to needing subclasses for Xanatars and now Tasha's.
Gloom Stalker, Horizon Walker, Monster Slayer, Swarm Keeper, and Fey Warden. Ideas after PHB.
The design space is massive
- Subclasses based on enemies (Hunter, Monster Slayer, Bounty Hunter, Giant Killer,)
- subclasses based on terrains (Gloom Stalker, Horizon Walker, Arctic/Desert/Forest/Plains Runner, Mountain Man)
- Subclasses based on the ranger's alliances (Fey Warden, Drakewarden, Seeker, Ranger Lord)
- Subclasses based on companions (Swarmkeeper, Falconer, Houndmaster, Liontamer, Drakewarden)
Plenty of design space untouched.
So hunting, exploring, hunting with a pet, and exploring with a pet.
I'm not entirely thrilled with this chosen design space. It's extremely DM dependant. If you're a forest ranger who hunts giants and you don't need to go to the forest or face a giant, what unique things can your character do instead? Nothing. And when you find a forest, what does the ability do? If it works nothing happens. The ability turns a potential encounter into
no encounter. Your class ability is to void XP. And if you face a giant, what can you do? Talk to it. That's the big benefit. You speak Giant. Your ability as a hunter is that you kind of know stuff about them, you know how to track them, and you can talk to them. You are the Diplomatic Hunter. In the game about fighting monsters, your really special skill is... avoiding adventure and talking to foes.
Except they can't really expand or alter this explorer-hunter role, because they run into Fighter (more martial), Druid (more nature magic), Rogue (more skill based), Bard (more hybridized), or Barbarian (more natural martial).