The context of close polygons is strange

This is due to the small size of the buffer that holds the context of the polygons (this buffer is called the depth buffer). I think it's probably the phenomenon below.

Socks and feet in close contact (16-bit)

You can change this depth buffer in the preferences. Select the one with the highest value of "D" from the list in the image below. This is the accuracy of the depth buffer. Also, this setting is not reflected immediately, so it will take effect once you quit the software and start it again.

However, the list displayed here depends on the performance of your video card. If there is only "D16", that is the only option you can choose. Ignore values other than "D" for now.

By the way, if you set it to "D24S8", it will look like the following.

* Basically, a high-precision depth buffer is used from the beginning.