I too think having a high-quality official onboarding tutorial is very important. I’ve mention this before, but it bears repeating in this context: the Svelte tutorial is by far the best official online tutorial I’ve seen for any programming language or package. (Svelte is a Javascript framework for reactive UI programming similar to React, but faster and simpler without all the boilerplate - much like Julia.) The tutorial is friendly, attractively designed, declares its prerequisites upfront and eases you into new concepts gently but still fast enough that you can complete it in an hour or two. It relies heavily on interactive illustrative mini-problems, so an online Julia version may have to wait until Julia works reliably with WebAssembly.
In the meantime though, it would be great if Julia had a downloadable interactive tutorial like this with a custom sysimage for instant startup. I don’t think it matters if it’s bloated to a few hundred MB, as long as it’s click-to-run, fast and nearly latency-free. I’d love to help design something like that…