Your post is really confusing. I don't know why you think state-of-being would be more appropriate.
In "ボブは、いつも勉強する人だ", 勉強する is not being used as an adjective, it's being used as a verb. It just so happens that verbs can modifiy nouns and noun phrases. (It's the same in English: Bob is a person who always studies. Yes, 'always studies' is describing Bob, but that doesn't mean that 'studies' is an adjective. Studies is a verb).
In Japanese, on the other hand, negative verbs literally ARE い-adjectives. There is no difference between an adjective and a negative verb. 食べない conjugates just like any other い-adjective. You can even double negate it! 食べなくはないけど ("It's not that I won't eat it, but...").
But look at 勉強する. Does it conjugate and act like an adjective? No, so it's not an adjective. 勉強しない, on the other hand, conjugates just like an adjective. The past tense is 勉強しなかった in the same way that the past tense of おもしろい is おもしろかった.
Your post is really
Your post is really confusing. I don't know why you think state-of-being would be more appropriate.
In "ボブは、いつも勉強する人だ", 勉強する is not being used as an adjective, it's being used as a verb. It just so happens that verbs can modifiy nouns and noun phrases. (It's the same in English: Bob is a person who always studies. Yes, 'always studies' is describing Bob, but that doesn't mean that 'studies' is an adjective. Studies is a verb).
In Japanese, on the other hand, negative verbs literally ARE い-adjectives. There is no difference between an adjective and a negative verb. 食べない conjugates just like any other い-adjective. You can even double negate it! 食べなくはないけど ("It's not that I won't eat it, but...").
But look at 勉強する. Does it conjugate and act like an adjective? No, so it's not an adjective. 勉強しない, on the other hand, conjugates just like an adjective. The past tense is 勉強しなかった in the same way that the past tense of おもしろい is おもしろかった.