Okay, I am confused. He's 5 and didn't understand what was going on at Christmas before this? That's interesting. I would honestly say by 3 most kids are going to remember the words Santa, Christmas, presents, and all the other words that we use specifically for this time of year. They would know and understand what is going to happen and get totally wired up in the weeks leading up to the actual day. Probably as soon as Hobby Lobby and Walmart put out the Christmas stuff in September.
So I do tend to thing he should have understood the whole concept and been looking forward to the stuff for weeks.
As for not finding his gifts to be just what he wanted they were certainly age appropriate and nice sounding gifts.
Is he in kindergarten? They do puzzles and stuff like that. If he isn't he may not have been exposed to them very much yet.
I enjoy puzzle games but sadly don't really care for actual puzzles. I love books and was always excited to get them. But since he can't read yet he may not think they are great gifts. He'll like them just fine if you read them to him and spend that time with him. That is the stuff memories are made of.