It's important to remember that stories like Gundam and Kamen Rider are so popular in Japan that they're ingrained in the culture to the point where anything could be a reference to them if you dig deep enough. Every culture is going to be like that. It's just easier to see those elements when you're on the outside looking in, especially when your knowledge of that culture is superficial.
Beyond that, it is impossible to create a truly original work because you're always influenced by something, especially narrative structure. Even if you think you've created something unique, how the audience interprets it is based on their own bias and experience.
And if you want to be really scientific about it, the human brained is wired for pattern recognition. Almost to a fault actually, because
we can see patterns that don't even exist.