Game View: no objects from the script, one created in the scene is just black stain

My script has already no errors but my nice object in game view is just a stain, no curves visible. How to improve it?

GameView shows always view from the camera that is not main one, main one shows the top of the object, how to switch it to main one? MainCamera is tagged as main camera already.

I can't see also objects created by the script that I put in empty game object. It is visible as objects originating in the script below but not in the scene or gameview. Yes, layers have clicked 'everything'.