I'm gonna devil's advocate this for a second.

Unless you're very poor (which is fair in most fantasy settings there's always poor people) magic kinda negates disabilities.

Like is there no spell that can cure these disabilities?

With that said to have that big of an issue with it just makes you an ass

Depending on the magic it might not make sense because people could heal everything, although you could explain it away by saying that the character could not afford a skilled healer.

I looked it up and the first known wheelchair that you could move yourself in was invented in the 1600s, which was after firearms became relatively common.

Im kind of ambivalent on this.

On one hand, ~medieval times, which are usually the general era and technology level the average fantasy setting plays in, have no concept of disability and people who have one are usually ostracized and/or begging in the streets. Blindness may be on the more tolerated side of things, but deformities or developmental abnormalities are definitely not accepted. Also, if there is magic why wouldn’t they use it to cure it?

On the other hand, it’s a fantasy roleplay setting and the primary function is to be fun. So if everyone agrees it shouldn’t be a problem to have a scenario with it, more power to you

It depends on the tone of the setting. Someone who gets their leg broken in a Forgotten Realms game can usually find a small-time priest to cast Cure Wounds on them, preventing most disabilities that aren't from birth. Someone who gets their leg broken in Warhammer Fantasy has to hope within their gimped traveling distance that there's a priest of the correct faith capable of appeasing the gods for the healing to happen, before their detriments become permanent. As such, having a disabled character in a game with more accessible healthcare requires an extra degree of explanation, on top of the PCs' and players' emotional response to someone being so downtrodden. The circumstances of their ailment, who or what was responsible, how they see their ailment and work around it, all are weights on the players' suspension of disbelief that a GM has to take into account that they generally otherwise wouldn't with John Miller, the able-bodied dude who runs the mill with a wife, three kids, and a problem with rats stealing the grain that he mills. It's like a Chekov's Gun in that sort of way, the GM as a storyteller surely wouldn't spend the effort to decide that an NPC has a trait that is notably separate from the default without it being somehow relevant to the plot. The mage asks the party to do a quest for their magical research, a general asks the party to do a quest for national security, and a person in a wheelchair... what desire do you give them that wouldn't be misconstrued as able-ist or a waste of that character trait? It's very difficult, often comes with an air of making some kind of a statement, either that they're a writer capable enough to wear disabled-face without it being offensive, or taking a preachy high-ground telling people a message about human sympathy, determination, and adaptability that they've already been made well aware of by the existence of popular culture.

I'm dreaming of a VR game with a disabled wizard who is confined to a chair and uses telekinesis or teleportation to move around. That would give the game a lore reason for VR locomotion.