There is some sort of parallel symbolism throughout the film which simply eludes me. The Broly/Goku relation symbolism is there, but I don't see it. The Frieza/Bulma 5cm/year tiny difference wish relation symbolism is there, but I don't see it.
I think the symbolism between Goku and Broly is just that they are kind of similar in which they are both pure-hearted.
The symbolism I found was between Paragus and Freeza, in which the movie sort of showed them to be similar in that they don’t give a damn about killing someone if it’s for their own gain, which also demonstrates how the Saiyans were never good people at all.
It is also shown how both Vegeta and his father have the kind of mentality that people will never change and have to be dealt with using rough methods (see how Vegeta doesn’t trust Freeza a bit, and was going for the kill on Broly) unlike Goku who always tries to see the good and the redeemable qualities (as he does with both Broly and Freeza, and as he’s always done before).
This behaviour of Goku is also in contrast to his late father’s, who sent him to Earth deeming him a weakling, in true Saiyan’s nature, almost as a way to have a little win over Freeza if he were to kill all the Saiyans.
It’s also reiterated when Raditz doesn’t give a damn about his brother because of his power - again, that scene when the survivor Saiyans are shown not to give a single fuck that their race has been wiped out truly shows just what kind of bastards the Saiyans were.
Maybe it’s implied that the Saiyans were like that not because of their nature but because of their culture, which is why Goku and Broly are so different from the average Saiyan?
I am sure the theme of the movie could have been conveyed better. We know that the original script was originally much longer, so I wonder if some stuff was cut that would have made the story feel more cohesive.
As for Bulma and Freeza, I thought their wishes being so similar was just a way to further emphasise the ridiculousness of Freeza’s wish.