WA Copying webapp/software ideas

[stevedoig]

Hi,

I aim to create a simpler web app inspired by a more complex one, incorporating some additional features of my own. General knowledge inspired the original web app.

From this page, I see that:

My own web app's

"work is considered original – and thus protected by copyright – if you use your skill, labour, judgement and effort to create it. Using another’s work is copyright infringement when ‘the work as a whole or any substantial part of it’ has been copied."

I understand that

The meaning of ‘substantial’ changes is defined on a case-by-case basis.

Given that the original app's central process is inspired by general knowledge, and I am using a much simpler version or process than the original web app and adding my own features, would my own web app break copyright?

The original web app is based in the USA.

(I originally posted this question on Stack Exchange)