Hi @redonihunter. Thanks for the correction about jams vs games on this site.
Your discussion of how to make games accessible when their core mechanic relies on ability is interesting. If you did provide options that "nerfed" your gameplay, does that stop someone enjoying the experience of playing it? I actually don't know. You the developer not cannot easily make judgements on the enjoyment that someone may get from playing it. But at least they can experience the game in some way. Take your example of a blind person and an oil painting or visual-based game. The accessibility is being able to give the person a description of it so that they have at least some frame of reference in which to understand it or talk about it with others. They're not left out. With my latest game, despite being a timer-based game, able people were asking for a slower or non-timed experience. Ability may not even come into it!
Of course there are problems if you bring people of different abilities together in some way, like high score tables or multiplayer, but there can be mitigations. But as you say, they take time and effort, which is difficult for the small developer. We do what we can, but it's important that we try to do it.
There are tools for checking some of these things. Colour blindness, contrast levels and text sizes/clarity can all be assessed just from screenshots with simulator tools. Designers usually have studied this a lot so that they avoid problems right from the start before it becomes expensive to correct. You'll often hear things like taking a mobile-first approach, because it's deemed to be one of the lowest common denominators with the simplest kinds of interaction and smallest screen real-estate.
This site is worth a read, just for awareness of things, https://gameaccessibilityguidelines.com/.