Texture distorted?

How can I undistort the Texture’s Image?

When I opened and create the texture for the model. the outline did not showed up so I went to UV editing and found out that all of the outlines were in the corner
Why does this happen?
Is there a way to fix this?

If you start modeling with primitives then a fairly suitable UV is already generated. But editiing and subdividing fastly leads to distorted meshes.
Although I don’t know how to exactly achieve such a mess as you, there is a way to fix it: UV unwrap.
See this blender tutorial for details: https://youtu.be/Y7M-B6xnaEM?t=280.

In short: in edit mode mark all and hit [U]. Use “Mark seam” to split the UV. “unwrap” or “Smart Unwrap” to well unwrap.