While undeniably and immaculate film, the Spongebob movie's final scene raises some questions.
Spongebob and Patrick's moustaches gives them an invincible level of self confidence. I think we can all agree that if they had their moustaches for the rest of the film, their quest would be over in no time. They would blunder obliviously through all the danger and defeat Plankton's scheme without fully understanding how.
In the final scene Spongebob realises that he is, after all, just a kid. This resolves his main emotional arc and is entirely thematic -- unlike what happens next. He turns into a wizard and magically saves the day. This resolves the film's practical arc, but seems to come out of nowhere.
While Spongebob's quest did lead to his final realisation it did not, at any stage, teach him the ability to transform into a wizard.
Ask yourself exactly what function the trench scene serves in the greater plot arc. . . .
Another point regards Dennis. Dennis is defeated accidentally by Spongebob 'blundering through' when bubble soap gets in his eyes. But this is not how he finally defeats plankton.
With all this in mind, I would expect an ending to look like this:
Spongebob has fallen into Plankton's clutches. Everything is lost.
Spongebob realises he was just a kid all along.
But a kid got to Shell city, and a kid got the crown, and a kid rode the Hasslehoff!
. . So I don't need to be a man to save the day again!
Spongebob proceeds to blunder through and save the day -- this time without a moustache.
The song is a reprise of 'Now that we're men' with different lyrics.
(6.5). The song itself is not what defeats Plankton.
I would not be surprised if the film originally had several endings, and the final one was chosen based on market research. Does anyone know what the other endings were?