Wow. That's pretty impressive already. The overall look is nice, I like that the characters share the same style with the background. The acting is good, arm movements are limited, but put to good use. You have avoided the effect of frozen characters when they're not talking. I'm interested in the characters, which is a good sign, the design is good, the head turns quite convincing. The overall timing is lively.
Now the "improvement part":
You shouldn't do squash and stretch on a head. Never. The head is a rigid body, it doesn't change shape. You can turn it, let it nod or shake or tilt it, but never change shape or size. (Only exception is for a comic take, but even that doesn't really fit in your style).
The same is true for the body: your characters change size all the time which is unnatural. Instead of this you should change body position: crouched down and straighten up, turn the body, stretch legs or bend knees.
The walk of both characters is not connected to the ground (the feet are slipping), and it has no weight. Have a look at some reference material, like this excerpt from Richard Willams here
https://bridgetharveyani210.wordpress.c ... vival-kit/.
The left character could do with better mouth movement, and there's some irritating blink in the mouth - a loose tooth? The right one is OK, but I notice there's no "o" shape. The lip sync could be improved.
I find the left character's voice irritating, it's the voice of a much older man. The recording could be better, I miss background noises, since this is a street scene. (A simple way to achieve this is to record the voices on a balcony or a backyard.)
The characters do not blink, nor do they move their eyebrows. This is both unnatural and a waste of acting possibilities (not too much - it's like spices in cooking: don't overdo it). The eye movements are a bit too smooth, but it fits with the style.
So, it's already pretty good work. Keep it up!