Juvenile Blackbird in trouble?

I have a juvenile blackbird (I think) in the garden who doesn’t seem to have any parents around, but is still at the fat and fluffy stage; he’s got a few tail feathers coming in.

We’re getting a little worried about him as he seems to just be hanging around in the border, and is usually very still. We put down some mealworms, some fruit, and there is a large dish of water, but he doesn’t seem to be very interested - he’ll peck at a worm or two, or a bit of fruit, but doesn’t gobble it all down like the others.

is this normal? We’ve been seeing him for the last couple of weeks or so, he seems to be very friendly and we can get much closer than we feel we should be able to - can anyone offer any advice or reassurance?