What am I?

I’m a little worm in the core of an apple
Rotting it from the inside out
I’m a little speck inside your brain
Who knows what the world’s about
I have all that’s hiding within
And everything that’s hiding without
I’m above, below, and in between
And everywhere throughout
I’m with the waking and the sleeping
Right there without a doubt
I’m there when you want the easy way
But know a better route
I’m where the land is lush and green
And hiding in the drought
I’m silent and soft and shushed out
But also scream and shriek and shout
I can be “fickle as a feather”
And eternally devout
I am the oldest sentinel redwood
And the smallest sprout
I am worth nothing all at
And have the utmost clout
I can bring a child joy
And make a titan pout
I am the king of all the land
And the lowliest scout
I’m as grand as the grandest grand there is
And as plain as your face’s snout