Thanks for contacting Lingvist!
We understand that you can find this example sentence a bit confusing: as proyectos is plural, then, it'd make sense that the noun following was plural as well. However, this is an exceptional case. Let us explain.
In this case it is not a matter of agreement between a normal noun and an adjective, but between two nouns: one with nominal function and the other with adjective function (in apposition). In such cases, if the second part of the compound does not function autonomously, it is left in the singular: e.g. días calendario ('days', but not 'calendars'); proyectos piloto ( 'projects', but not 'pilots').
Regarding the grammar tag (ADJ), we have modified it in our system (normativo/a can also function as an adjective, but not in this case). As for the translation, the term normativa is a collective noun, which means it refers to a collection of things taken as a whole. Thus, it usually translates into English as a plural noun:
– normativa vigente: "current regulations"
– normativa conjunta: "joint regulations"
First of all, thank you very much for reaching out to us!
Regarding your question, both Todas las personas son distintas and Todas las personas somos distintas are correct sentences. The only difference is the speaker's emotional distance towards the message contained in them (somos implies less distance than son in this case).
We will modify the translation so it conveys the meaning of the example sentence in a clearer way.