why did the british think their military forces were superior to those of the americans?

Question

To which time period or war are you referring?

??

The British had an old style of fighting. They fought traditionally in battle lines. The british thought that their style of fighting was the way to go and anything different was lowly. The Americans had cruddy uniforms and fought "gourilla" style. This means that they hid behind trees and walked through swamps.

Ahh, Revolutionary War?

... and guerilla warfare?