It better to have mistakes in our first try than have a mistake later. We learn a lot when mistakes occurs early because we can able correct them before we proceed toa more challenging paths. I never regret also if I have done mistakes in the past because that was one of my best learning experiences and you can't able to succeed in the future if you will not learn from your past.
Regret as known as FOMO is a normal feeling when you realise that you have made a mistake, more or less obvious. You should also distinguish your decisions that were leading to mistake. Some of them could be too risky and inappropriate unlike those that were suitable but didn't turn into an optimal as a result.