some nouns are irregular and allow that to work sometimes, like "moose", you can say "look at all the moose", but can't say "look at all the mooses", because the plural of moose is moose. Might be confusing, but their are some special cases, like: (moose, deer, buffalo, fish, and more) !
If I understand your question right, here's my two cents.
Some words can definitely be used in the singular to refer to a class - in other words, to refer generally to that sort of thing. But it does not refer to each individual example of that thing.
The car is an amazing invention. = Cars, in general, are amazing. Cars are amazing. = Cars, in general, are amazing. Every car is amazing, no matter how cheap or worn-out. = Refers to each example of car in existence.
The tree is a marvel of evolutionary design. Trees are beautiful, no matter how big or small. Each and every tree is beautiful, no matter how big or small.