My son is six months younger than yours and came home a year ago. He was in a hogar for the first 14 months of his life. I just wanted to tell you that a lot of the things you're seeing in your Jesse, I saw in my son as well. Everyone always commented on how even-tempered he was, that he seemed so content with whatever situation he was in. I saw indifference, and sometimes just plain unresponsiveness. The creative/imaginative play thing --- absolutely!!! After being home for a year, he has just started to develop the ability to play like the other kids at daycare. He now makes planes fly, cars "vroom", and pretends he's swimming in imaginary water. Three months ago he wasn't doing that. He is still content to play alone, but interacts with others much better. Please remember, some of this is just normal toddler development, too. Like everyone is saying, give Jesse some time and you will see amazing things blossom in him. His personality will surely astound you everyday. Just expect delays and be glad that you'll be there to witness so many of his firsts.
Please keep us all updated on his progress. I'll be thinking of you both.