"Because it is interesting, I study Japanese."
Kara here is used to tie together reason between action and main theme. Omoshiroi kara - due to [the theme] being interesting. Nihongo wo benkyoushimasu - studying Japanese.
It usually helps to read the sentence backwards - it would be something like "I am studying Japanese because of its interestingness".
When you think of から also being used as 'from' the order makes sense too.
The way I heard it, which helps me, is to think if is like "so"
So it would be something like "It's interesting so I study it"
Why is the sentence structure like you translated it literally from Japanese? It's not natural English.
I think so. I'm Chinese. That is one of the English structure accepted when we were taught, but now we know it's not natural lol.
This is a pretty unnatural sounding English sentence. We would more naturally say "I study Japanese because it's interesting", I'd suggest.
No, you cannot. You can say 'omoshiroi desu (the sibject you are talking about is interesting). But by using 'desu', you are completing the sentence. When you use から (explaining the cause), you need to continue the sentemce.
For example, びょうきだから、がっこうをやすみます。Because I am sick, I won't/don't go to school.
When we explain the cause, you can also use なので、or だから as well. I hope it is not too much...
When I was reading about Japanese, it told me to use だから like "because" or "therefore". Can から and だから be used interchangeably, or is there a nuance between the two?
The だ in だから that you're thinking about is in fact the informal form of ですanyway. It's most common to use polite forms in sentence endings and informal forms everywhere else, but you can in fact use formal everywhere in some cases like in business correspondence and news broadcasting, etc.