Nothing wrong with the theory but the series of events don't add up!

Rating: 8/10 (13 December 2014)

**SPOILER ALERT** There are spoilers!
I loved the movie. Its intriguing and is whatever positive thing its projected to be.
But the storyline isn't consistent.
Theory of Manipulating Time:
The theory of manipulating "time" - the forth dimension - is represented by the tool of light-wave-look-alike moving images where he communicates with his daughter ahead of time through gravity. Yes, I do acknowledge and accept this theory.
However, the series of events don't add up: NASA sends astronomers ending in failure and death. Cooper is sent meanwhile daughter is contacted ahead of time. He finds "4D". His assistant robot claims it was created by a generation of humans "they" in the future ahead of cooper for him and his daughter.
First, There is no sense to create a tool for him and his daughter as it has consumed years for him to reach that tool as Earth is running out of resources and people are dying. Why wasn't NASA contacted as there is a board who can collectively receive similar gravitational messages and probably would understand it much quicker.
Second, if cooper is portrayed as the hero and savior of Earth, then there aren't any predecessors before him reaching that far in space. In other words they failed. Now, how was he the first to succeed in space then finds a tool (4D) of which his failed predecessors created? But if you say his predecessors succeeded and took the luxury of time to create a tool of 4D, then where are they in the present day where he - cooper - was in space? Well if "they" were on Earth during his explorations in space, then how the hell was the 4D tool created in the present if they - his predecessors - were on their bottoms on Earth? That means they didn't precede him? But if they were his predecessors they wouldn't be in the present crying out loud for survival?