I have never seen a Jaques Tati film, so i really can only guess his character from this short clip alone. To me, he seems to be a kind, gentle, friendly and patient man. We see him giving a gift to the girl who obviously wanted a tomato, we see him interacting pleasantly with the neighbors. As he walks up the labyrinth of steps and hallways to his apartment, he does so with a calm, patient manner. The adjustment of the window is funny because it is only after a bit that we realize he is trying to give the bird below some sunlight. At first we have no idea why he is fussing with the window. He kindly takes the sticky candy from the girl and acts pleasant about it to her, though he obviously doesn't really want it. So i would say he is kind, patient, gentle, and mild mannered.
The style of the house - the labyrinth of stairs and walkways - is of course absurd and comical. The design is clever because the windows and spaces allow us to see his progress on the inside from the outside, all in one master shot. We see him almost the entire way, and when he disappears he pops back up somewhere else in a comical way. It reminded me of a Rube Goldberg device, in that you progress through seemingly useless complexity simply to get from one point to another.