Those run-on sentences hurt my brain.
No, you shouldn't try to deadlift with a round back, even if you pick up most things in the real world with a rounded back. This isn't functional fitness. The point of the deadlift is to make your back stronger so that it can handle the real-life stuff a lot easier. When are you ever going to lift a 300 pound box by yourself? Or a 400-pound human? Most of the things we pick up in day-to-day life weigh less than 100 pounds. How much easier is it to lift those things when you have a 500-pound deadlift?
Picking things up with a rounded back isn't what usually causes spinal injuries--it's the active flexion and/or extension of the spine during the movement. So, if you pick something up with a rounded back, keep your back round until you finish whatever you're doing. Don't pick up an object by flexing your back first, then extending it to move the weight. You see this when strongmen competitors lift the stones. Their backs are rounded and stay rounded until it's time to load the stone onto the platform, where they then finish the movement by extending their hips. The back doesn't lift the stone by going into extension.