On our November trip DD was a month younger than your DS will be ( 13 1/2 months) and on our February trip she was 16 months. Both trips she LOVED Dumbo and the play area inside. My DS10 and I both went up in it with her....she never wanted to leave! She also loved Aladdin's carpet Ride, Swiss family treehouse ( she has loved stairs since 11 months) , jungle cruise, the carousel, little mermaid( but she loves princesses), loved buzz light year. In Epcot Nemo was eh, but the aquarium was a huge hit for her, Frozen was great and first, then at the turn with the snow monster not so great. AK was great, she loves animals and lived triceratops spin. She was tall enough at 16 months to do Alien swirling saucer at HS and loved it, but didn't like Toy story ride.
My DD is way more adventurous than DS was, and very social.
She loved dancing to any music playing and saying hi to EVERYONE that passes us. 6 months was much easier for me than her 13 month old trip, but the 16 month old trip went smoothly....you all are going to have a great time again! We still didn't so Night time shows

and kept to her schedule. She watched the MK fireworks from the room for about 6 minutes a couple of nights, that's the extent of our night time activities though. Have a magical second trip with your baby boy!
Edited to add on my DD 6 month old trip pirates didn't scare her, but she cried on both the 13 month and 16 month old trips on that ride.
At 6 months and 9 months we did what we/ DS (then 9) wanted. On her last two trips though, ( 13 and 16 months) she loved rides and definitely wanted to participate in going on them. Huge change after she turned 1, so I would expect DS to really love it this time!