I for one am glad they aren’t going with the always perfect, above everything Superman. He wasn’t raised a Kryptonian, he was raised as a human and humans aren’t perfect.
Gunn did a great job showing that not only can Superman lose physically, but mentally as well. It’s really the hurdle you have to clear whenever you are dealing with his character.
Showing him battling his emotions sets up better for later issues when people like Batman start pushing his buttons.
And no, Superman wasn’t Starlord, Green Lantern was Starlord.