OK this is probably not quite what you meant but I'll shoot: I highly recommend Terence Tao's Analysis textbook (which now also has a Lean counterpart on GitHub). You can skip Chapter 1 (it sets up the motivation but I couldn't answer most questions, which is part of the point). From Chapter 2, it builds up in a somewhat "dry" but actually very accessible and methodical way. It is "mathematical" but it is "for people who don't know mathematics" in the sense that it forces you to build the entire mathematics from scratch, including proving things like `a + b = b + a` as exercises. This is actually how I got into proofs in the first place, with later picking up Lean by doing Natural Number Game.