I didn't even know that poem exist. I have always heard my brother recite those lines and asked him to tell me that poem about Africa. And since 12 lines was demanded I added my words to fill in those gaps.
If you had noticed, some words were not rightly written, until I followed that link provided that I knew someone wrote that poem and that I even made some mistakes while writing out some words
Plagiarism means you start with something that someone else created and make it your own. Whether you copy it exactly, or modify it, it's not yours. You will always be muted and/or downvoted or blacklisted for doing that.
Start with a blank page, and fill it with your own words. Otherwise, you are stealing.