to be high: to rise up or be lifted to a great height, whether in physical elevation, in honor, or (most often) in pride
The picture behind this word is simple and physical: something rises far above the ground. A mountain, a wall, a tall tree, the heavens overhead, a head that stands above the crowd. That literal height is the root of everything else the word does.
From there the same word reaches upward in two very different directions. It can describe genuine exaltation, a person or thing lifted high in honor by God, and it can describe the swollen self-importance of a heart that lifts itself up. The Bible plays these two off each other constantly: the God who is truly high brings the falsely high down. The context, not a change of vocabulary, tells you which is meant.
By far its most frequent use is the negative one. Again and again the word describes a heart that has grown proud, and it almost always comes paired with the fall that follows. To be high, in this sense, is to be headed for a crash.