It is legal to rewrite other people's articles. It's it ethical? It depends on how you did it. A professor of mine once said, if you copy the work of one person, it's plagiarism. If you copy the work of multiple authors and put it into one article, it's called research.
Therefore, what you should do is to get information about one topic from different sources, and from that, you could create an entirely new article. And of course, the most important part is, you should not forget to cite your sources and if possible, include a link back to their original articles. That's the ethical way of doing it.