I'll recommend Uwe Flick of Cambridged if you're interested in the notion of representation and identity.
Like all art there are actually limits of what our subconscious minds can perceive. Mario is, by choice, very simplistic, so it is hard to for any conclusions that, most likely, wouldn't already exist in the human mind. Though I guess there might be an inherent hope of good prevailing over evil embedded in the "story".
In order to have subtext you require a text, a narrative, and Mario games tend to lack those (I am saying this having played no modern Mario games). To summarize, subtext requires narrative, Mario has limited narrative so the subtext will be limited as well.
Even if the movie isn't meant for kids some are bound to watch it, but besides those, the adults watching it will, excluding evangelist and people who push their own insecurities on others, hopefully reach one of the following conclusions, though hopefully both.
1. Children are exceedingly sexualized and shouldn't be.
2. Children want to achieve something and they want something that is separate from their daily lives and makes them special, not matter the cost.