What Is the Universe at Its Basic Level?

It seems like a human species, we've been sort of breaking matter down little by little over the centuries, right? I mean, before we thought that things were made out of water, air, earth. And then we found out about particles, and then atoms, and then sub atomic particles,. It seems like we're breaking things out more. We are digging deeper into nature of reality. But there's also another direction that's really interesting for thinking about this problem, which is going the other way, starting from the smallest bits. What can you make? Like if the universe is made out of legos, what kind of stuff can you buildy? Because it's pretty mind blowing