Hey, nice starcraft vibes here!
I like the thing with selecting transportation for the robot. Very very long ago I thought there must be some RTS that has just regular guys be produced, and then you equip them manually with bow/sword. This has some of that :)
Some things i would have loved:
The music should not be a 2d thing! There is the AudioStream2d component, and the AudioStream component. The latter should be used for music!
If scrolling with mouse, then fullscreen would have been much better.
Also, clicking single units would have made wonders for my "split" with the workers.
Rally points would have been good too. Level 3 got really hard. Some way to rally new robots would have helped.
I think you should look at nav mesh, or its 2d counterpart. The robots did not find good paths, so I suspect you rolled your own when there is a very competent system for just that in godot.
Nice submission, and fun to see some RTS!