So, "the father" is something like "Not just any father, but a particular father, and we can assume that we both know which particular father we're talking about."
Next time anyone says "language X is so weird, they have an expression for Y!" think about how to explain "the" to, say, speakers of Mandarin. :)
a -> yige "一个"
the -> zhege "这个"/ nage "那个＂
And of course words like "my", "our" which are used in place of articles are there as well.
You might not need the articles when the context is very clear (which causes problems for Chinese speakers when they try to learn English), but the concept is there. I believe it's the same in Japanese. Can't comment on other languages though.
So, to an English learner coming from these languages, a sentence like "I was cleaning attic and found book" is perfectly understandable. Exactly what attic and what book we're talking about should be apparent from context.
On the other hand, in actual English, "I was cleaning the attic and found a book" portrays a different picture from "I was cleaning an attic and found the book." Use one when the other is warranted, and it sounds weird and confusing.
Both "a Kevin" and "the Kevin" would feel weird, especially "the Kevin". One might do it on purpose as a sort of joke, implying that Kevin is an ordinary inanimate object.
More oddness is that "cleaning up" doesn't involve an "up".
"Who?"
"Elvis"
"Elvis? The Elvis or a Elvis?"
"The Elvis"
The doesn't imply someone is inanimate, it just means that they are a specific one.
English is quite varied; takes similarly to eliding subjects, at times.
Now, I don't generally have to worry about gender (per se) in most of my nouns but it is bloody hard remembering whether a table is masculine (DE) or feminine (FR, IT).