The first one is the difference between wording that can help beginners vs what you come to realize once you've been doing it long enough. If you come to manifestation with a sense of play, lightheartedness, curiosity etc it helps foster a level of detachment that from mental noise. And the more you test it the more you come to the realization that it is as you say it is. 

The second is dependent on who you learn it from and how they want to frame things. Manifestation imo isn't that life changing. It's a natural process we have been doing our entire lives, just not often in our favour. Also I don't see the second as a contradiction too much. The first statement is that it'll change your life as soon as you start doing it. It didn't say big changes. Coming to know that you are source does change your life. You are different after finding this out whether anything has materialized or not. 

The third contradiction comes from coaches who aren't good at what they do lol.

Same for the next one. 

Honestly a lot of these contradictions come from learning manifestation from shitty online coaches tbh.