Thanks for all the help! I’ve definitely got a long way to go.
I think I get the structure for simple sentences; for my next trick, I’ll try leaving off the subject:
ビニール盤の採集を面白がる。
Intent: I enjoy collecting vinyl records.
My vocabulary’s still somewhat limited, so I’m pulling a number of these words from online dictionaries for now.
I think you got it there!
面白がる confuses me a bit though (not because of you, mind you), because every dictionary I check lists it as an intransitive verb (meaning it doesn’t take an object) but every example sentence gives it an object… So I’m just gonna say that sentence is probably grammatically correct 
I don’t know if it’s particularly natural though. I feel like 面白がる is more leaning towards finding something funny or amusing, like a joke or a story, or going off the meaning of 面白い (the associated adjective) it might also mean you have an interest in something, as in the idea of something interests you. So maybe this would indicate something more like you haven’t started a vinyl collection yet, but you find the idea appealing.
Maybe 楽しむ would be a better fit here, indicating it’s something you consider fun to do. And I might be inclined to use an adjective (ビニール盤の採集は楽しい) instead of a verb, but I’m not sure what a native would think and/or what the difference in nuance would be. Maybe the adjective makes it more of a general statement (it’s fun) rather than a personal thing (it’s something I enjoy doing)? In which case a verb might fit your intention more.
ところで、どんなビニール盤を採集するの？
By the way, what kind of vinyl records do you collect?
You make a good point about using an adjective as opposed to a verb; there’s probably some nuance between the two.
主に、クラシックロック採集する。じゃっかんジャズも。
Mostly, I collect Classic Rock. Some Jazz too.
色々な興味が多いので一つの趣味に捧げるのは不能だ。
I have so many interests so it’s impossible to focus on one hobby.
大学に行ったけど面白くなかった
I went to college, but it wasn’t interesting
There are some intransitive verbs that can take objects, but they remain intransitive, because still the person carrying out the action is also the target of the action (in a way). For instance:
家を出て、駅へ行った。
I left the house and went to the station.
授業に急ぎ足で出た。
I left for the class at a quick pace.
Theoretically, neither the station, nor the class were the target of “leaving”.
休む can also take an object when it points to taking a break from something specific. But to me both 出る and 休む feel a little special in this respect 
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The way I understand 面白がる is that it means “to amuse oneself” using something as the source (?) of amusement.
ビニール盤の採集を面白がる。
can be put differently as:
レコードを集めるのが楽しい。
Collecting records is fun (to me).
or
レコードを集めるのを楽しんでいる。
I enjoy collecting records.
But neither are the object either, right? The only grammatical object I see is 家 as the object for 出る (which, admittedly, is intransitive too) - 駅 is marked with へ, 授業 is marked with に, neither of those are object markers, right?
Yeah, that’s part of where my confusion comes from. I see both taking an object occasionally, but… why? Does that mean they’re not really intransitive? And does the same apply to 面白がる? How can you tell which verbs work that way?
In the case of 出る to me it feels slightly colloquial, the same way one would say it in English. But for instance 降りる takes に when pointing to what kind of vehicle one gets off, and 乗る also takes に.
I honestly can’t tell which verbs specifically work that way until I see them in some sort of context and try to make sense out of the sentence, but I’m slowly trying to divorce the meaning of を as a particle that always points to the direct object and/or defines a verb as transitive and then it kind of makes sense.
第十章の文法：
９）～（という）のは事実だ
１．ナイル川は世界中に一番長い川のは事実です。でも、いくつか人がアマゾン川方が長いことを信じます。
２．佐藤と道子は恋人というのは事実が多い男性と女性は羨ましいです。
３．この高校には男性と女性の関係は許すというのは事実ですが、セックスはとても禁止です！
「燃焼」から「弟子」まで落ちたほど今夜言葉のレビューを負けました。
皆は風に砂がいます。
先月故障した冷蔵庫を替えるように頼んだのに、まだ大家の返事がない。
Though we have asked to replace the broken fridge last month, the landlord has not replied yet.
昨日の夜 jam plugをちょっとやってみました。初めてだったので怖いなってと思いました。慣れるいけないと！
Yesterday night, I tried using jam plugs for a bit. It was my first time, so it was pretty scary. But I have to get used to it!
I’m not entirely sure what your intent was with this sentence but I don’t think that’s quite right - what did you mean to say?
lol I was aiming for “All we are is dust in the wind.”
皆 I understand as being “all/everything/everybody”
風に砂が was intended to be “dust in the wind” (or more literally “in the wind is dust”?)
Ah, gotcha!
That’s a tougher one than it seems actually, because you can’t translate it too literally. Either way いる is not the right verb to use here for “to be” - いる is more of “to be” in the sense of “to exist”, not as in ascribing a quality to something. You generally want だ or です for that (or any of the other copulas you can use depending on politeness and context but you’ll get there later - だ for plain, です for polite is all you need to know for now).
皆 is indeed “everybody” but the “all” in your English sentence is not so much to indicate that everybody is dust in the wind, more so that they are dust in the wind and nothing more than that. 皆 is not the right word to use for that here, what you’re looking for is probably だけ or しか〜ない, both meaning “only …” or “nothing more than …”. I’m not entirely sure of the nuance but the example sentences I find for both suggest to me that for this case しか〜ない is more appropriate. More reading on both: https://maggiesensei.com/2016/06/08/how-to-use-しか-だけ-shika-dake/
Now, depending on what you’re trying to express you can use 皆 for the subject to express that everyone is just dust in the wind, or you can say something like 俺ら to express “we” (I went for a casual form here because this doesn’t seem like something you’d say in a very polite conversation, you could also use something like 私達 to be more polite). I’m thinking it’s more of a general statement so I’d say 皆 is more in line with what you intended.
For “sand in the wind” I can see why you went with 風に砂 but the “in the wind” part is attributive to the sand (i.e. describing the sand in some capacity) so you can say something like 風の中の砂 to indicate “the sand inside the wind” (that’s a bit awkward in English but that’s more or less what the Japanese boils down to) or you can say something like 風にある砂 (sand that exists inside the wind, also a bit awkward in English). I might be tempted to go for the second - I feel like the first more or less implies that all of us together comprise all of the sand in the wind - as in, the sand in the wind and all of us are one and the same, whereas I think that saying more or less expresses we’re all a part of the collective “sand in the wind” (if that makes sense).
If that distinction is bullshit, feel free to call me out on that, I’m not basing it on much here.
So what I’d go with is 皆は風にある砂しかではない - more or less literally, everyone is nothing but sand that is in the wind.
I might even say you could take a bit more liberty and reform it to “we are nothing but sand being scattered by the wind” where I’d go for the progressive passive form of 吹き散らす (吹き散らされてる) and make 風 the actor for that with に:
皆は風に吹き散らされてる砂しかではない
This explanation is so good it deserves to be in the Hall of Fame.
Oh wait, I can do that 
あそこに椅子があります。
This is an amazing explanation! 
I was actually curious about the translation so popped it into Deepl which is usually quite good even with more elusive stuff and it suggested 塵 (ちり) for “dust”. This is the full output:
It feels fairly accurate and even uses 我々 instead of the lower suggested 私達.
The other alternatives used のように like this:
私達は皆、風の中の塵のように。
or
私達は皆、風の中の塵のようなもの。
@Takeshidude you can use 皆 like in the above sentences, so not only as a topic of a sentence where you indicate that an anonymous “everyone” did something or is involved in something, but also to indicate “all the people” when talking about the number of people.
もの as @yamitenshi explained earlier is one of those “thing” placeholder words which can be used instead of the actual matter being discussed or to express something more abstract. It’s either もの or こと. I have no idea what the nuance is 
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I think もの (物) more often refers to objects and living beings, whereas こと (事 ) more often refers to actions (most notably as a verb nominaliser) or more abstract concepts (like when you say 君が好き - I like you, the physical person vs 君のことが好き I like you, in the more abstract sense of your personality, what you do, etc. - what makes you you)
Also 塵 is much more fitting than 砂, didn’t even think of that
EDIT: found one source that supports that: 物（もの）vs 事（こと） - Grammar - Kanshudo
Which doesn’t make it guaranteed to be true of course, but at least it’s not completely out there 
