If you want to create new articles you should certainly have an account to show you're serious. Fill in your user page to demonstrate some authority. You should get a 'global' username so it's the same on all language sites; that may be the default now - I don't know.

I've created a few pages - but years ago, in more trusting times. I often copied an existing article with a suitable format and edited it. I used to copy the entire article code into a text editor, edit it offline, then post it up and preview it before publishing. I'm not sure whether you could do that these days - wikipedia has become stricter. (To see the complete code of an article, add #/editor/all to the URL.)

There are guides and howtos in wikipedia, there must be one for creating articles, so I would start there. I think there is a sandbox to play in. Or you could just jump straign in...

Choose a name for the entry (get that right) and construct a URL for it, such as

https://en.wikipedia.org/wiki/Songs_by_xxxxxxxx

One of the options you then get is to start a new article with the wizard. I've never used it, but give it a try.

The motto of Wikipedia is, or used to be, Be bold! Don't worry too much about the rules - provided the editors think the article is worthwhile and you know the subject they'll probably help by formatting it and adding stuff like categories. If you get criticism, don't let it get you down.

You could create a basic article using the wizard, just the introduction say, then copy in and edit single sections from similar articles, such as the list part of the Roud songs article.

When editing articles, you may have to tread more carefully. I've had cases where people have reverted an edit of mine - but their edit summary should say why. I've reverted edits on 'my' pages; they're not really mine, of course, but I created them because I know a lot about the subject and I don't want trivia added! Other people do the same - I've come across some very posessive and stubborn users. Look at an article's history: what sort of edits are rejected and why?

I don't see the edit referred to on that Es ist ein Ros entsprungen page - maybe it was long ago. But I can see that 'yet another' example of the use of a song might not be welcome. You can re-do an edit, explaining why it's worth including. You can engage with the other user on their talk page. But unless you feel very strongly it's not worth getting into a 'revert battle'.