When an edit is rejected by the Community, it was automatically rejected because it conflicted with another edit.
For example, the original poster could have been editing the post at the same time, and that edit wins when a suggested edit conflicts with it. In this case, there was an another suggested edit that won; that one was submitted later by someone that must have opened the editor before your suggestion was submitted. Because the other edit was approved before yours, yours lost.
Suggested edits normally need two approve or reject votes before its fate has been decided; your suggestion already had one approval vote before it was automatically rejected. You cannot do much about such rejections, it's just bad luck if it happens to you, it has nothing to do with the quality of your edit.
How to avoid these kinds of conflicts? The only way to avoid them is to not make edit suggestions at all; there always is a chance someone else submits an edit around the same time. That chance diminishes as the post in question ages, of course. Once you reach 2k reputation you can edit posts directly and you'll be notified during editing if someone else submitted an edit at the same time.
Note that the Community Moderator also rejects an edit when a reviewer has decided to improve on your suggestion but mark the suggestion as not helpful. In that case, the edit history will show another edit that coincides with the rejection of the suggested edit. This was not the case with the specific suggestions you posted in your question though.