I bought a LG UltraFine 5K display for use with my MacBook Pro. The question: if I needed to, is there any way to connect it to a 12" MacBook (I have the original model). Clearly not in 5K, but at a lower resolution?
No. You'll see people claiming that you can get it to work with a Thunderbolt 3 to Thunderbolt 2 adapter, but that's not true. The MacBook doesn't have Thunderbolt 3.