So for each real person that will give you feedback you will come across another that just go from game to game and comment "really great, had fun" or some surface level thing on 300 entries just to as you say "self promote". Some people will always treat jams as competition and with the amount of kids in here, it'll happen even more. You're also looking way to much into these comments.
What I recommend to you is to go to twitch (search for brackeys) or search this forum for some people playing the games live. These are usually some small time creators with few viewers that will take jam entries and play them live. This is the most honest and interesting way to see your games. The reactions are more honest, they actually take time to play the game because you know - you're there watching, and you can actually converse with them about the game, ask them and answer questions. I've had the most fun watching others play my game and I've learned the most.