Then you still don't have the grounds to say this is disappointing. You can only be disappointed when your expectations are really high. I don't know how you can expect lots of scenes when this is a 3D open world and he is only ONE developer. Even then, he said not all the scenes have been added, which is why this is in ALPHA.
Minor correction to this point, the credits list separate people for character modelling, rigging, and animation, not to mention character design + voice + translations + music though most of those have some degree less direct involvement in core dev work.
Anyway, very technically impressive 2nd demo. It'll be a miracle if such a small team working in UE manages to implement even a quarter of what they clearly seem to have planned, though, with all the map/objective/world/swimming(?)/inventory features added. Definitely feels like there's (still) an extremely high risk of random feature creep bogging it down even on top of the inherent insane difficulty of accomplishing things in UE.