Okay, so spoilers on from this point, but then again the movie has been released quite a while ago....
Atlantis/Lemuria is an interesting theory, however, I believe the movie was quite clear about the explanation. Also, evolving into beings capable of perceiving higher dimensions is a long-time SF trope, and Nolan was very clear about his intentions to pay respect to such things. Sure, one of the most obvious influences is 2001 and Clarke's vision about the higher beings was different; but the ability to 'see' through time was a necessity for the story, so he kinda had to include this.
As for Interstellar in general, I think it's a fundamentally flawed movie... It has a lot going for it, but Nolan decided to focus on this emotional guiding force and derive the rest of the story from that. Love as an actual aspect of the universe was kinda too much. Still, most of the audience loved it, so we could say that it worked...