It's been a while since I've had a dream that I remember that detailed. I could see colors, there was grass, wind, the sound of leaves blowing in the wind, I could turn around and see a building behind me.
after thinking about it for a while, I've come up with what I think it might have meant: just my opinion.
I personally enjoy scenery like that: wind and the sound, but as I looked back at the building I paid no mind to why it was there. I was just trying to find out what I could do in this state of awakened dreaming.
I should have used that time to figure out how on earth I ended up in such a real state while asleep (even to this day reality feels like the dream and the dream feels like reality; its like after that night both of them mixed together sort of, in terms of perception)
Maybe I couldn't fly [as you put it] because I was not used to being that aware in my sleep, and because it appeared so real, and the awake reality is what I [can remember] experiencing the most, I weighed myself down by rules that didnt apply to the place I was in.
in other words, I treated a lucid dream like reality, and got a weird mix of lowered gravity instead of flight when I tried to fly.
It's like that scene from the matrix when neo tried to jump buildings: He wasn't used to the rule changes.
Hopefully I'll have more dreams like this, more often, and hopefully astral projection too.