Are all those three screenshots for the LG UltraFine 5K?
Last picture shows the resolution is only 4096 x 2304 and the pixel click is only 593.82 MHz (instead of something like 900+ MHz). That SwitchResX screen is probably the only way to check the resolution and frequency. Framebuffer size does not always equal display resolution. The OS can scale a framebuffer up (to display a low resolution on a high resolution LCD) or scale a frame buffer down (to display a HiDPI resolution that is not exactly a half of the display resolution; for example, in your second screenshot, the 3360 x 1890 hiDPI resolution is actually 6720 x 3780 and is scaled down to the display resolution which is probably 4096 x 2304 as shown in the third screen shot).
USB-C displays use DisplayPort alt mode. A USB-C cable has 4 high speed lines. In the case where DisplayPort alt mode is used, there are two possibilities:
1) Two lines for DisplayPort, two lines for USB 3.x
2) Four lines for DisplayPort
Both options include USB 2.0. The LG UltraFine 4K uses the latter.
The Thunderbolt port supports USB devices and docks, USB-C displays, DisplayPort displays, USB-C display adapters, Thunderbolt devices, docks, and displays. So it should work fine with the LG UltraFine 4K. The LG UltraFine 5K should be connected to a different Thunderbolt port that has two DisplayPort inputs to achieve 5K 60Hz resolution.