Let me say as kindly as I can: your little guy is giving you quite a show!
Let me also assure you that we preschool teachers have seen this before. The NAEYC has a great pamphlet on goodbyes that I wish I could send you. In a nutshell, it suggests that we give our child our confident goodbye and pass them off to the teacher, tears and all. If you check with the preschool teacher, you'll likely find that the tears subside soon after you leave.
In my experience, even with the children who had the biggest tears and wailing during drop off, this lasted about 10 minutes at most. Littler children, I would help to get engaged. Sometimes, some children refused to participate, at which point I would find a quiet chair where they could sit alone with the option of looking at books until they were ready to join us. The point of it was that they had a choice to sit and cry or to move ahead in our day with the group. This was never done as a punishment but simply to give context: we can have upset feelings but we do not get to control the whole room with them. Eventually each and every child would join the group.
Some kids need to get this "I'm mad about not having the world the way I want" out of their system from time to time. Good for you for not pulling him out of his current situation. I see this as one point in a long career of education for a child; if we pull them out at preschool because they fuss, they are going to expect to have a similar influence when they become older, which will then become more trouble because at those ages, schooling is compulsorary. We go to school because it's what we do, just as you go to work because that's you do.
If you feel there are no red flags regarding his preschool/staff, then keep doing what you are doing. Do not let your son's temporary drop-off outbursts undermine your feelings or confidence about what you are doing. Too often, I see parents question their own judgment because of their child's opinions or feelings, which can be very hard for us. I'm a mom, so I know this too. Children are meant to push against us and our values from time to time. They also need us to stand firm in what we do and say, otherwise, their whole sense of foundation and firmness crumbles. No matter what they would like, should we let them make the choices or be the boss--it might be fun to a child, but deep down, it's terrifying for them. Working and dropping my son off was terrible some days. But I'm his mom and know how to make the best decisions for my family--- and you do too.