For the last almost 20 years, I've had a new vehicle either every year or every other year and have never seen oil this black on a first oil change. I haven't had the oil tested, but I'm guessing I wouldn't like the results. Why people wait more than 1-2k miles for the first change is beyond me.
I think the initial fill is conventional oil. My oil was black when I changed it at 7500 miles but who's to say it still wasn't effective? It doesn't take much discoloration for oil to be black when it's in volume and in a dark container. How did it look on the dipstick? Mine was dark but didn't obscured my vision of the dipstick.
My last truck was a diesel and each oil change was 4
gallons. Granted it was a diesel but the oil was pitch black on the dipstick within 500 miles.
So many variables make it hard to generalize: did the sump get filled low or high in spec on the assembly line, how long did it sit before it was shipped to the dealer lot, how hard was it test driven, how long did it sit between starts, etc.
My truck had just over 40 miles on the odometer when I bought it but it was 5 months old when I bought it and I have no idea how it was treated before I got it. Since then I changed the oil at 7500 miles and every 10K after that. I just turned 50K miles this week with no issues (PUP oil and Mobil 1 filter since 7500 miles).