Sometimes a smooth progression of difficulty is what you need to learn something, and this looks like it fits that bill.
I don't think it's for everyone, though — not that it claims to be. I can tell right off that I'd never finish the sequence. There are people who do better thrown in at the deep end, who find motivation in working through mounds of complexity to accomplish a goal that's interesting to them.
Maybe you don't end up with a perfectly rounded set of skills, but you do end up with an interesting result and the ability to accomplish some things well beyond what you have any right to be doing. If you watch for the right opening, you can make yourself very useful.
It also has some worthwhile projects that can grow into something of your own. Like, the elevator simulator could be made into some kind of game, etc.
You could use different languages, frameworks, etc. or polish your skills in something particular that your team uses.
Here's the original list that the OP mentions: https://github.com/florinpop17/app-ideas