The Team Tsathogga characters are mostly level 2 (although a few of them hit level 3 at the end of our last session), so level 1 spells are all that they've had access to so far. But they're moving through a world in which most people don't have any magic at all, and their ability to cast spells like Charm Person, Comprehend Languages, Cure Light Wounds, Detect Evil, Command, and even the humble Light (which should really be renamed 'Light or Darkness or Blind' - it really is the Swiss army knife of level 1 spells) has allowed them to set themselves up as virtual gods. They can conjure mystic light from heaven, or summon darkness at noonday. They can heal wounds with a touch. They can translate ancient inscriptions in long-dead languages. They can strike men blind. They can locate the source of the evil forces plaguing the community. They can turn foes into friends with a word and a gesture. They can order their enemies to kneel before them in battle and actually be obeyed. No wonder everyone they meet is terrified of them.
|The epic duel of Bargle and Aleena. Remember them? First-level spells all around!|
Later editions of the game gave out so much more magic, to PCs and monsters alike, that these spells became little more than parlour tricks - in fact, when cantrips became a thing, some of them ended up getting demoted to level 0. The low-level B/X cleric or magic-user, able to cast only one or two first-level spells per day, became a figure of mockery. ('Remember when wizards could only cast Sleep once per day? Man, casters used to suck so much!') But put them in a relatively low-magic world, and they don't feel weak or comical at all. They feel like miracle workers.
Of course, B/X casters aren't that hard to deal with if you know what you're doing. They're usually pretty soft targets: snipe them from range, or catch them in ambushes that drag them straight into melee, and Mr Beard and Bathrobe will be splattered all over the walls before he has a chance to get off a single spell. My PCs have been absolutely ruthless in dealing with enemy spellcasters, to the point where the first time they learn what spells they could cast is usually when they rifle through their stolen spellbooks. ('Hey, this guy could cast Charm Person! Good thing we shot him first, right?') But 'in the wild', as it were, the addition of a single level 1 cleric or magic-user to a situation can be an absolute game-changer.
I know it's long been D&D tradition that every village priest is a spellcasting cleric, and that every town has a local wizard, and so on. But if you want your PC casters to feel like badasses right from level 1, try putting them in a setting where that's not the case - and then watch just how fast they wreck it using nothing but first level spells...