Musa/Moses (may Allah be pleased with him) was given the mighty task of conveying the message to the biggest and most evil oppressor of the time – and that was Fir’aun.
Musa (as) had a speech impediment so if we can try to imagine how he was today, maybe he would have come across as being a shy person with a stutter, so in the eyes of other human beings, maybe he wasn’t the ideal person for conveying a big message. However, Allah chose him and that makes him more than ideal – it makes him perfect.
I think this should inspire confidence in the rest of us, that the loudest voices aren’t necessarily the most able. They may come across as being competent and perhaps in many ways it is easier for them to assert their views, however, quiet people can be just as good a leader/messenger. They should be able to speak up against evil and tyranny when the situation requires, even if it means people will not take them seriously. Being quiet or introverted does not mean that one is relieved of the duty to stand up for good.
I think there are so many beautiful lessons in Surah ash-shuara. The example of Musa (as) should inspire and motivate us because it shows us that he also felt fear and worry. These are normal human emotions. However, we are required to act in ways that defy what we are feeling or thinking inside. At the end of the day, Allah is judging us for what we do and not how we think or feel. At least, that’s what I think is the case. Of course, I have a lot to learn and the journey continues inshaAllah.