Perhaps there is a young child who is about to enter kindergarten or first grade. They would be very likely to experience first day jitters. Or it could be an adult who has just moved to a new city and is starting a new job. The main characters are usually those who are in a situation of new beginnings and are feeling nervous.
Without reading the 'first day jitters story', we can't be certain. But it might be a character like a transfer student. This student would be experiencing the jitters of walking into a classroom full of strangers, trying to find their place in the new school's social hierarchy, and getting used to different teaching methods compared to their previous school.
Another factor is the pressure to perform well. There's often an expectation, whether it's from yourself, your parents, or your teachers, to do well academically. On the first day, this can translate into jitters as you think about all the upcoming assignments and tests. Also, social concerns play a role. You might be nervous about making a good impression and being accepted by your peers.
The main themes could be about new beginnings, nervousness, and facing the unknown. New beginnings because it's the first day, which often represents a start of something new like a new school year or a new job. Nervousness as the word 'jitters' implies being uneasy or worried. And facing the unknown since starting something new usually comes with uncertainties.
Well, it could be about a variety of things. Maybe it's about a student's first day at a new school and all the nervous feelings like not knowing where the classrooms are, being worried about making new friends. It could also be about someone starting a new job, feeling jittery about meeting new colleagues and getting used to the new work environment.
One way to overcome first - day - of - school jitters is to be well - prepared. Make sure you have all your school supplies ready the night before. Also, try to familiarize yourself with the school layout if possible. For example, if there's an open house before the first day, go and explore the hallways, find your classrooms, and locate the cafeteria and restrooms. This can make you feel more at ease on the actual first day.
Not having read 'the first day of winter story', we can only speculate. It could be a young couple who are having their first winter together and are learning to enjoy the cold days and long nights. Maybe there's a local guide in a small town who shows the newcomers around during the first day of winter, and that guide could be one of the main characters. Or it could be a family with a small child who is seeing snow for the first time on the first day of winter, and the family members are all important characters in the story.
The Pilgrims were a major part of the story as they were the ones starting a new life in America. And the Native Americans, like the Wampanoag tribe, were crucial. Their leader Massasoit played an important role in establishing a relationship with the Pilgrims. Squanto was also a key figure as he taught the Pilgrims so much about survival in the new land. So, these were the main characters in the first Thanksgiving Day story.
I don't know specifically without reading it again. But in Decameron stories, there are usually characters like noblemen, ladies, servants, etc. Maybe there is a young hero and a beautiful heroine in this story.
The main character is Gogol, of course. However, there could be other characters who are crucial to the story. For instance, if it's a story about his first day at work, his boss or a mentor figure might be important. Or if it's in a social setting, the people who welcome him or those he has his first interactions with are also key characters. In general, the people who shape Gogol's first day experiences are the main characters in this story.
Clifford himself is surely a main character. There may also be his teacher.