I would have to see the occlusal (chewing) surface of the incisors to age them as the galvynes groove is not that accurate. A non blurry nice close up of the surface of the uppers and lowers would be good!
at a long shot (but really cannot see that well from pics) it could be 4 as the corner 03 incisors (the edge ones) are shed at 4 1/2 but I cant tell if they are soon to shed or are immature adult teeth that have already shed and are not in wear yet in which case around 41/2-5. How old were you told he/she is?