Wikipedia is and has always been a wiki; reverting bad or controversial edits has always been expected from day one.

Also Wikipedia has developed an editorial line of its own, so it's normal that edits that go against the line will be put in question; if that happens to you, you're expected to collaborate in the talk pages to express your intent for the changes, and possibly get recommendations on how to tweak it so that it sticks.

It also happens that most of contributions by first timers are indistinguishable from vandalism or spam; those are so obvious that an automated bot is able to recognize them and revert them without human supervision, with a very high success rate.

However if those first contributions are genuinely useful to the encyclopedia, such as adding high quality references for an unverified claim, correcting typos, or removing obvious vandalism that slipped through the cracks, it's much more likely that the edits will stay; go ahead and try that experiment and tell us how it went.

I’m here to let you know you are wrong.

I made an anonymous edit to the Wikipedia page of one of Hemingways short stories three years ago, and my edit is still there.

I’ve made several edits to wiki-pages without even having an account. A few got reverted, most stayed.

Some pages/topics are more open to changes than others, that much is true.

Start with the "practice" articles that Wikipedia suggests when you begin as an editor. They might be stub articles, or articles with obvious issues, that you are expected to research and improve a little. Then edit articles where you have more domain expertise than the original authors.

They have strict rules, but I’ve had no issues editing articles after my first error. It’s certainly not like posting an answer on Stack Overflow, where you will be downvoted and flamed for a correct-but-suboptimal answer.