Lv 1 doesn't necessarily mean "clueless nobody who just started adventuring".
DnD allows you to create a character with an already rich backstory, full of a prior life, and that doesn't have to translate into "high level".
For the purpose of "ludonarrative cohesion", it is easily reconciled: Your character simply decides to employ abilities of increasing power just as the threats increase that require them (and as their "XP", as a representation of that, increases as well).
Correct me if I am wrong. But, you are saying that my wizard posses the ability to cast fireball and time stop, they just choose not to because the threat is not high enough? why would they risk their friends, using some minor spells when they fight 30 goblins, when they can end it fast with a single spell?
