I know from personal experience that school children on a bus are very annoying so I started thinking how I could make it different. I thought if the school goer was a mid teenager and quite attactive this would break with convention and suprise the audience. Obviously this is only a rough sketch and it is likely to become a group of young annoying children.
I then thought about the lead character. I wanted him to be a normal everyday 'bloke' so that the audience goes on the journey with him and finds some of themselves in him. In this way he is indistinguishable, he has no outstanding features and had plain (probably cream and brown) clothing so that we as the audience can put our own image onto him.
I thought as a plot point throughout the film he could be waiting to get to a destination, but he has to travel the whole length of the journey so quite a way to get there. In this time he is dozing off and constantly trying to sleep. He keeps being interrupted by the school children and a screaming baby and a chav playing loud music.
For this, he looks quite annoyed and grumpy. He has tired eyes due to lack of sleep. He would probably be between 25 and 30 and feel like he is too old to still be taking the bus, but could be a mature student or someone working class that cannot afford a car. His clothes are also plain to emphasise this.