That's How Pyramids are Built

Oh, congratulations!
I wouldn't know what to suggest specifically; there's definitely always an "add more content" approach, but going with what is already here, deepening mechanics may just be enough: the people are a very good game piece, so I think they are 100% fine. The plant is odd, because the stone it gives you is random and it doesn't appear when it's first placed, so it often creates bad surprises. Additionally, the situation where it opens up and bridges a gap seemed pretty rare. Perhaps the plant would be able to place tiles in more flexible ways, "intelligently" finding a spot where it could put a stone without dropping it. Weather mechanics are also pretty good, especially as you begin the game and some conditions block what you do. As the game goes on, they're more of a detail, however. Perhaps rain could form puddles when it cannot drain between stones, forcing you to make space for drainage, or to use plants to remove it (it could be a very simple tile based simulation, nothing like fluids, even). Perhaps snow could pile up, taking longer to melt the more there is; to manage that, you would have to make sure your cat priest perches in multiple spots, as it would bring the sun around itself. Lightning strikes are fine as they are, I think :) Finally, the cat priest could have additional behaviors based on where it's placed - I mentioned bringing the sun to it, maybe stone patterns could also have small benefits or disadvantages, such as influencing the time people and plants take to crumble or grow, not falling if they lose their support. With all of those combined, perhaps the game would be able to be played for a bit longer, with variations to how you approach challenges.
Those are just my first ideas :^). Regardless of what you plan with this game, I will keep an eye out for what you make next! This is the sort of thing I'd volunteer to code, were I not also busy with multiple other things... :)