Before i start, i want sorry because my English is bad. Ok let’s start.
I want explanation about Envato Terms who said, “The items you upload for sale must be your own creation. Do not submit works based on tutorials or other people’s designs.”
The words “Do not submit works based on tutorials or other people’s designs.” mean i cannot use Bootstrap framework or any Jquery plugin? And of course before i understanding about using Bootstrap, we must see tutorials for use Bootstrap or any Jquery plugin.
Once again, sorry because my english id bad.
Thanks 
Frameworks like Bootstrap are fine.
The rules are talking about other people’s designs, code tutorial e.g. Codrops etc. rather than base or open source code.
so i allow to use another Jquery plugin owned by others (open-source plugin)?
It depends what it is and the license around it. In most cases open source is ok (as long as it is being included in a bigger item and not being sold ‘as-is’) but not all allow for commercial use so best to check with he author.
If it is from CodeCanyon for example then you would absolutely need to have the authors permission.
Thanks charlie 
One more question, can i inspired another work in Themeforest? (of course not 100% identical)
That’s a very dangerous space.
You will see several themes which may be “inspired by others” but the more you do this then the less chance you have of being approved, and potentially sell, and go too far and could end up in serious trouble
Charlie, you say code tutorial e.g Codrops, as well W3schools? Because i learn Bootstrap from that place.
Bootstrap is fine. Although you will need to style is propeely to fit your design.
I mean like you can’t download a gallery from codrops and sell it as it is