In Spanish, it's common for double negatives to not actually be double negatives. For example, if you wanted to say "there's nothing here", you'd say "no hay nada aquí", which word-for-word means "there's not nothing here".
Checking out the Royal Spanish Academy, here's what they say about it:
> The so-called "double negation" is due to the obligatory negative agreement that must be established in Spanish, and other Romance languages, in certain circumstances (see New Grammar, § 48.3d), which results in the joint presence in the statement of the adverb no and other elements that also have a negative meaning.
> The concurrence of these two "negations" does not annul the negative meaning of the statement.
Same in French: "Je ne sais pas" means I do not know, not I do not not know (aka I know).
In any case, the meaning of the sentence above: "uno no es ninguno" in Spanish is clearly one is not zero, or one is not none, or one is different than none.
"Uno no es nada" could be "one is nothing", and "one is not nothing". It all depends on the frame of reference (in this case English), but for this sentence, the "one is not none" is correct IMO. I would never even do a second pass on that sentence, as a native Spanish speaker (appeal to authority, I know)
Checking out the Royal Spanish Academy, here's what they say about it:
https://www.rae.es/espanol-al-dia/doble-negacion-no-vino-nad...
> The so-called "double negation" is due to the obligatory negative agreement that must be established in Spanish, and other Romance languages, in certain circumstances (see New Grammar, § 48.3d), which results in the joint presence in the statement of the adverb no and other elements that also have a negative meaning.
> The concurrence of these two "negations" does not annul the negative meaning of the statement.