I think I could say something like "differing opinions/perspectives/thoughts/etc." I'm wondering if I could somehow say this with one word?
I can't think of a single word.
The phrase for the meaning you're describing is De gustibus non est disputandum, or sometimes colloquially "to each his own".
This is not however the literal meaning of 人各有志. The most analogical word is aspiration in English; e.g. "each man has his own aspiration".
人各有志 I think is 'everyone has ambition' or, as Yang says, 'aspirations', but in English this cannot be condensed. How would you run 'everyone' into 'has ambition'?
De gustibus non est disputandum = 'There is no accounting for taste.' but 'each to his own' has that sentiment.
人各有志 is a idiom.
I will simply use "Our paths depend on what we want." or "Diversities among us creates possibilities."
Probably a variation on concur... like "unconcurring" or something like "incongruent", but it would depend more on the context. Do you have more of the sentence that you can show me?
I don't think there's an idiom in English as such. If you have to translate it, perhaps "pursue your own dreams" would be the closest. There is however a common saying "don't live somebody else's life", which gets the gist of it.