My wife drive kids to school daily, total distance is about 4 miles. The car (2014 Mazda 5) doesn't even properly heat up, most probably. So her average mpg is around 16 with such usage. When traveling on highway, I remember we were getting something around 25 or so.
When I drive my 2008 Mazda 5 for 3-4 hours straight, mixed highway and city (ride-sharing, basically), I get around 26 (top I can remember).
So, I would say, yes, this is sort of normal mpg.
You can try cleaning your throttle body and air intake, I think it can increase mpg a little bit. Definitely wouldn't make it worse.