I'm saying that even the mind isn't certain, and even nothing, which goes even further than Solipsism
This is what Solipsism ends up with, which is why it is nonsense. But anyway, if that is not your position that is fine.
You're making the assumption that life must make sense, but life doesn't have to make any sense at all, which is why we must have faith that it does to believe that logic is real, because evidence cannot be evidence of itself, as that is circular reasoning.
Life doesn't have to make sense, the reality you live in has to.
This eventually ends up with the essential question of what is the meaning of life?
To me, to answer this question you first have to split it into 3 categories depending on what life you are speaking about.
1. Why is there life in the Universe?
2. What is the purpose of life?
3. What is the meaning of your own life?
The answer to the first one is that we don't know. And the answer might never be known and it might in fact turn out to have no meaning at all.
The answer to the second one is also unknown and doesn't really seem to follow any rational path, it simply grinds along. What I mean by this, is that I don't think any species, except maybe humans to some degree have an overall plan or strategy for its own survival. Meaning I think it is fair to assume that for instance turtles or other animals don't go around worrying about it being important to make sure that their species survive. They mate with each other without any grand goal in mind. The reason I say that humans do this to some degree is because of our brain which allows us to think abstractly. But even we have our limits, if you for instance were stranded on an island after a catastrophe your goal wouldn't be the survival of the species rather it would be purely about your own survival. But as long as we are not pushed to such limits we can think more abstractly.
The answer to the third one, I think one can logically arrive at, simply as being happy. This would apply to all people regardless of who they are, murderers and none murderers. Doesn't matter, if you wake up each day being happy, whether that is by hurting other people or not, then you essentially are living the life you want. Obviously, this might sound absurd how murdering other people could be meaningful. But looking at it from an individual perspective, what makes one person happy doesn't necessarily have to make sense for anyone else.
But none of these offer any explanation for making sense of life. Either they are unknown or not really explained. The 3 one probably being the one that at least offers a hint of sense, as you can make the argument, that since you are stuck in this life anyway, being happy rather than miserable is more beneficial for you than not be.
I have faith we exist despite not knowing.
What is reality to you?
However, it could be that knowing things is actually possible, so I am not actually certain that people cannot know anything, as I am uncertain of everything and even nothing)
If reality is the current state in which you live, then you can know things within it. Whether it is actually real or not, doesn't matter. Assuming that our reality is a simulation, it wouldn't matter, because the reality in which we live is what it is.