***** NOT A TEACHER *****
Dear Fellow Parser:
May I comment on No. 4, since what that sentence says is so true.
1. I believe that the "skeleton" of the sentence is:
Humans + can be + animals.
a. Humans (noun phrase) = subject.
b. can be (verb phrase) = (linking) verb.
c. animals (noun phrase) = subjective complement / predicate nominative.
(i) ridiculous = adjective that modifies "animals." (What kind of animals?)
(ii) fairly = adverb that modifies "ridiculous." (How "ridiculous"?)