Top shirts from Wannashirt on 1 March 2020

This is sometimes known as plot armor, and sometimes known as Mary Sue syndrome, depending on the way the author idealizes or protects the character. I won’t go into the details of the definitions because they’re not as important as the idea that you might be tempted to make the character perfect and unstoppable in a conscious or subconscious effort to protect yourself and make yourself look good. This can backfire and readers will complain about things like how all the other characters in the book are in love with the protagonist and that the protagonist can do no wrong in anyone’s eyes and that the protagonist always effortlessly wins fights and so on.
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How you handle your character is entirely up to you, and how readers receive your character is partially dependent on how good an author you are and partially dependent on what they as readers bring to your story. I’m absolutely not saying that if you base your character on aspects of yourself, or the plot on things that have happened to you, or both, that your book will be horrible and boring, and your character will be a Mary Sue, and that you’re going to get one star reviews. Like others who’ve answered your question have pointed out, a lot of authors include their own life experiences and their own personalities in their plots and characters.