I don't understand why Light travels at the same rate regardless of the speed of the source or observer?

You're right, it is counter-intuitive, but it's nevertheless true. The speed of light is a fundamental property of the universe, and, as far as present-day theory has it, cannot be exceeded by significant amounts of matter. And, as you said, it remains the same regardless of the speed of the source or observer. I know, it's weird!