Also I'm currently watching and I'm going to be adding any little things I see, sorry for the double post lol
1. The time-lapse: It's a good idea to speed it up, but I'd recommend getting the replay mod rather than just your perspective! The replay mod is wonderful for youtubers' time-lapses! The camera moves around and you can speed that up to show what you *and* your son are doing from a different perspective. A building youtuber "Grian" uses it wonderfully and it's very enjoyable to other time-lapses where I always feel inclined to skip over it and see the finished project.
2. Another part on the time-lapse, if something interesting happens such as, like in the first episode, you found a mob head, Maybe record in first person and quickly switch between it for us to hear your reaction.
3. Around the 10 minute mark the time-lapse cuts you off while speaking; I feel as though a cut like that is a bit jarring, so I'd recommend trying to make the editing a bit smoother. I also noticed a bit after that you accidentally duplicated a word you said, which was a bit odd.
4. Just looking at the times for the other videos I'd say to cut them a bit short. A 20 minute episode should be the cut-off point. Keeping people interested would be the top priority for the beginning of your channel. Pewdiepie can get away with 40 minute videos because his personality and videos are very well-loved and established, people enjoy the longer videos.
5. Mining obsidian doesn't take all that long, but it's longer than a lot of people's attention spans on youtube. Maybe tell a personal story, maybe your dog got out and you had to go chase it. Maybe your cat did something funny. Personally, two people laughing at a story in a video is much more funny than in a solo person telling a story. Laughter is quite contagious, but hard in a solo video.
I think that's all I'll write for now, hopefully some of these tips will actually help.