I don't have that creative part of the brain but admire those that do. I have to follow the instructions step by step or my kids lego sets are jacked. I almost inevitably mess up or there are lost pieces and I end up in a fit of rage and have to basically start over because my stupid brain can't just look at it and figure it out. I am jealous of those that find this stuff relaxing.
Building sets with instructions is like super easy, even the adult complicated ones are relatively easy and lego has gotten so much better at it ove time. Bags with numbers, an instruction set you build in piecemeal in a logical order? When I was a kid it was just a grab bag of bags you you had to search, it made it much more difficult. The worst set I've built was the statue of liberty ones because all the green and like the same 5 pieces got hard after a while.
I think you just have to have enjoyed it as a kid. To me it's therapeutic, kinda like hand drafting. I think it's the ability to see tangible progress without a lot of effort that probably is the sell for me.
To me the hard part is if you want to make something new on your own, it's the real big step, to me lego sets teach you techniques. When you create something 50% of the battle when you have a giant box of legos is finding the right goddamn part, the other half is learning to implement those learned techniques on something new. Once you get good at it it becomes fun again but it is hard right out the gate. That is kinda the cool thing about like lego masters or the lego movie explore, the "follow the instructions" vs "figuring it out on your own", it's just a big part of life, and design in general.