Yes, there are some unobservable aspects of our bodies. And they are… unobserved! So, we don't know about them, yet.

But we find unobserved aspects about biology every few days, just read the science papers and you'll find that easily.

No it's not correct to presume that “we are infinite”. Firstly because infinity is just an idea and can't be found anywhere. And secondly because what's infinite is a “container”, so it's not a thing, a thing is a “contained”. And we are things, obviously, because we have a physical body.

Therefore we are limited.