they honestly could be fruit flies. Kids left some bananas out to long a month ago. I have only watered once so its not over watering.
I can not tell which variety I deal with by seeing one around, but:
Fruit flies mostly fly around rotten fruits and vegetables, if any around. I see them around that kind of stuff, rarely around plants. I have not experienced any harm and have not read about negative effects.
Fungus gnats go for wet soil and lay eggs in it. I thing I had their visit once some time ago, flies were mostly interested in soil area. Wet, of course. very wet.
Aphids are more tough and I have been fighting with them for some time. I spray plants when I see one, very short push to the button and mist lays down on plant, all animals are killed in a second or two. Despite all care, control and immediate action, I still see one or two occasionally. Aphids do nothing serious in small quantities, and can be very, very annoying if they get out of control. But luckilly, as Waira says, theyare slow movers.
Aphids are in form of flies and little animals, 0,5 mm long, which can not fly yet and eat and shit around leaves. They target young plants. At the beginning, I thought they were little stains on leaves, and then one of these stains moved.
Or maybe you have got something else around. Whatever it is and no matter how unharmfull, you had better get rid of them, if possible.
Good luck