That's a terrible observation I've made in my short time as a developer. Is it possible that in code/programming, everything is copy and paste, that is, the changes between one application and another are just replicas of each other's source code?
I see this a lot in practice when I have questions about a function or component and I go to Stack Overflow to look for a solution to this problem, and there is the answer.
When that's not the case, many of the projects are similar to each other in their code, operation, command lines. For example, take a tutorial on how to make an audio app using React on Youtube. Take about five videos on Youtube and watch them. You will see that there is a lot of similarity in the code and past teaching.
This all makes me think that (I don't know if this is absurd) code is part of a pre-established pattern, and it is. It's no use wanting to invent some code for an action where that code won't work in your application. There's no way around it, it's just copying and pasting, and it's no use insisting on the "puritan" speech of "original code".
Despite this dispute, it is possible to develop applications in an "original" way. Often a change in design (UI/UX), page style (CSS, SaaS), or adding an animation can make a difference.
I believe that in this way, what would be a "copy and paste", finally becomes an "original" project.