@dana_w
Let's approach this from the "missing icons" direction...
I started writing a guide to checking you have all the icons installed (for me these are in C:\Program Files\GIMP 2.10\share\gimp\2.0\icons)
BUT I've now realised that you're missing the standard GTK icons - which are not supplied as separate icons for the Legacy theme - they would be complied in, So I have to ask where you got your GIMP installer and exactly which version of GIMP you've installed? i.e. 2.10.2
Also, what Theme do you have selected?
Let's approach this from the "missing icons" direction...
I started writing a guide to checking you have all the icons installed (for me these are in C:\Program Files\GIMP 2.10\share\gimp\2.0\icons)
BUT I've now realised that you're missing the standard GTK icons - which are not supplied as separate icons for the Legacy theme - they would be complied in, So I have to ask where you got your GIMP installer and exactly which version of GIMP you've installed? i.e. 2.10.2
Also, what Theme do you have selected?