Is there a limit to Human understanding?

Considering we are on just one small planet surrounded by billions of stars. In a galaxy surrounded by billions of galaxies that are too large to comprehend it seems to me that there is probably a finite capacity of what human beings can actually know about everything and nothing.
Surely we cannot be the most perceptive and complex life forms that exist within space and time.
What makes us so important and so worthy that we should even destroy the very thing that gives us life? Our own planet.