Two days is very new, it usually takes about 2 weeks for them to settle into a new home.
He is probably still very much in the kennel routine (I presume he was in kennels), he needs to get into a set routine. Also if they are kennelled with other dogs around them they learn to bark LOUD to get attention. My dog used to try jumping on me at 4am, he soon stopped when he heard the bad language! Seriously, he will settle down, just be persistent. DON'T whatever you do feel sorry for him, what you let him do now he will continue to do. This is day three of his new life, the rules are set now, start as you mean to go on.
Labs love food so a Kong stuffed with cheese and paste and anything else he might find attractive will almost certainly keep him occupied. Also when you are out take a pocket full of treats and train him (even sit, wait, down etc.). As he becomes more secure around you and realises he is here to stay he will settle more. (Imagine if someone came and took you from your house without saying a word and dumped you in a big mansion house then left you all alone! Imagine how scary that would be, you don't know where anything is, if anyone else is in there or anything, or if anyone is going to come back!). Leave him in one room, where he has a bed and feels secure.
I am sure he will settle soon and you will have a lovely companion! Good on you for taking on a rescue!