For those of you asking about the magic-user's usability at low levels
For those of you scratching their heads how can a magic-user be used without magic, maybe you are not the target audience. And that's perfectly fine!
The magic-user is intended for resourceful players who like to strategize and fiddle around their limitations. Not every character class is equally difficult to pilot. On the opposite end of the spectrum is the fighter, meant as an everyman kind of adventurer who can pick up anything and work with it, but he has no other special capabilities outside his equipment.
Here's some things for the magic-user to consider. For a start, his prime ability is intelligence, meaning he knows lots of languages and can read, write and solve riddles. Maybe even has extensive professional knowledge like history, architecture, legends and lore, etc. Depending on how other players roll, the magic user may be the only one literate in the party!
As for the combat stuff, he can throw a bunch of daggers as a ranged attack. Keep in mind daggers do not disappear when thrown, unlike arrows or bolts which break upon impact. He may also use splash weapons, such as burning oil or holy water. At level 1 all characters have the same shitty base to hit bonus, so it boils down to a small difference based on stats. By the time to hit bonuses become relevant, the magic-user will already have a wider range of magic at his disposal.
A magic-user may set up an ambush or some simple traps when the party hears someone approach, and he can just as well search for traps, hidden doors and hidden features as well as anyone else.
So to sum it up, a magic-user is someone you play if you want a thinking challenge, not a straightforward answer. The harsh limitations are supposed to be a part of the experience. If you are to unravel reality later on with your magic, you need to learn how it operates first, and you do so by getting to know the world through overcoming adversity with wit and ingenuity, not raw power.