Idk man, it seems pointless to make ascertains about the nature of the universe. I don't really know much, so I'll quote Feynman about it.

“Are you looking for the ultimate laws of physics?" No, I'm not. I'm just looking to find out more about the world and if it turns out there is a simple ultimate law which explains everything, so be it; that would be very nice to discover. If it turns out it's like an onion with millions of layers and we're just sick and tired of looking at the layers, then that's the way it is. ... My interest in science is to simply find out more about the world.”

There's no way to know if there is a fundamental ground level, we've definitely thought we found it many times before. I mean, atom literally means indivisible, and boy was that wrong. It seems to me to make less sense that the universe is perfectly curated for humans to be able to grasp the outer boundaries (both micro and macro) then for the universe to the endless and, much like the universe, there's a limit only to what we can perceive.

Regardless though, certainty is something we will never have.