I've memorised the keyboard shortcuts that I need in order to do this extremely common thing.

1. Select region with mouse.

2. Ctrl-C: Copy the region.

3. Ctrl-V: Paste (with the selection still active, so that it pastes in the same place).

4. Ctrl-Shift-N: Makes the resulting "temporary layer" into a permanent new layer.

5. Use the new layer.

I wish I could skip step 4. It's usually not necessary, and if I need to place the temporary layer into the same layer that I was already using, I can just merge the two myself.

Of course, sometimes you do need the ability to directly paste into the same thing, such as if you're editing a layer mask rather than the actual layer itself...