They really do. I'm always nervous about the saying the wrong thing in social situations, even online ones. When I feel I've made a mistake, even something really petty, I feel like I've lost the opportunity to make a new friend. I try to remind myself that everyone makes mistakes and that generally people aren't *that* judgemental. A lot of people would be accepting even if I make mistakes.
Hi there! Being yourself, and authentic with the people around you, and with people who you would like to get to know better as friends, are going to be the things that will carry the day. If you make a mistake or do something that you feel or see hurt someone, or makes them feel disappointed, genuinely apologize, and try to learn from it. If we would never make any mistakes, we wouldn't learn much about ourselves, or even about others. You said something important already: everyone makes mistakes, and if you know that others would still be accepting, that's all that matters. Don't worry about your past mistakes, or the what ifs. Take what you have learned from them forward.