Land is a type of capital, landowners could produce agricultural products, accrue wealth, and debt was a thing back in the day as well. Often projects would be bank-rolled by wealthy landowners or even royalty (who accrued their wealth by taxing others). Labour also used to be extraordinarily cheap (or free). Go back far enough, everything was produced by individual labour, and things were simply traded for other things.
How did western economies function prior to this? I wish I was educated on the matter. I've not found good reading for this topic outside of the enclave of academia.