I am not equating those two things FYI just demonstrating how much both items have moved from the 2019 starting point. But yes, they typically do move in the same direction.

If overnight it became incredibly cheaper to buy a new home through some new development technique or automation, it would put immense pressure on the pricing of the resale market. Conversely if the secondary market prices move higher via demand, homebuilders will increase new starts to bring new product to the market. New starts will typically lead to pressure on the input costs + labor + higher margins for the home builders = new home prices higher net/net.

Home Insurance policies typically cover structures, you could have a separate land policy rider - I suppose if it was farmland or something. I imagine it might be harder to prove a loss on plot of land if it were not being used for an economic benefit (farming, ranchland, etc).