I’m not sure what you expect vegans to eat then. They can only reduce the harm they cause so much. Drawing the line at creatures that move around and actively interact with their environment, including avoiding injury and reacting to negative stimulus, is easier than trying to subsist on, like, nothing. As for bacteria, we can’t like, see them, or avoid them. It’s literally impossible to not ingest them. Plus the only time we actually target bacteria is when it’s harming us, and it’s not like vegans don’t believe in enacting self defense against something that attacked you first. But we can pretty easily avoid eating jellyfish. It in fact takes more effort to eat jellyfish than it does to not eat jellyfish. I mean you can try to get pedantic about it, like whether plants avoid negative stimulus or whatever, but again, vegans have to eat something, or they’d, y’know, die. Jellyfish can have an observable avoidant reaction to harm. It’s a relatively simple line to draw when you have to draw one somewhere.

And no, you can’t hurt a chair, because a chair is an inanimate object. There are humans who don’t have the ability to feel pain, but that doesn’t mean that they can’t be hurt, as in harmed. It also doesn’t make them the same as a chair.