When do babies start to actually eat?

My son is almost 7 months old. We started solids at six months (he is interested and definitely ready for it). We do a combination of purees and blw. The thing is, he doesn't open his mouth. He puts the food to his mouth, but he doesn't usually open it. Same with spoon feeding, he will grab the spoon and put it to his mouth, but he doesn't open his mouth. I mean, it does happen, but it's very rare. So, the amount of food he gets is so very little still. I know you shouldn't compare, but I can't help but to notice other children his age seem to actually be eating. Help?