In many fantasy rpg videogames your first companion is a childhood friend from your village, or a fellow academy graduate or something similar. They are there to help you survive the prologue/introduction arc, and they tend to either be very plain (basic human fighter, thief or cleric, no interesting background) or jacks-of-all-trades who aren't very good at anything, but can fill several roles (wizard-thief, cleric-thief...etc).
After the prologue they tend to leave the party forever, but, if they don't, they are often sidelined in favor of sexier, flashes, more useful, more powerful, more interesting companions. They become pack mules to carry all those extra potions and scrolls you will never use but keep just in case, and these cool but weak weapons you like to keep even if they aren't useful. They are left at the camp every time, and they are equipped with stuff you no longer need, like, you pass them your Gauntlets of Ogre Power +4 after you get the +6 version.
At first glance, it looks sad, but it's a sweet deal, really. That character will reach max level without doing anything, get world-class gear for free, and the stuff in their backpack is worth a few villages.
Do you remember any isekai with a similar premise?
Art is by Basedbinkie, by the way.