That depends on how you look at it. Wan was the first Avatar, there were no predecessors, followed up by 10 000 years of Avatar-generations. Regardless whether Korra has contact with them or not, she was not the first Avatar. She can however be considered as the first Avatar of a new cycle, Avatar 2.0 if you will, if she doesn't reestablish her connection with her past lives as the line got temporary broken and reforged.
Still don't like it though. I read somewhere they confirmed that she will not be able to contact her past lives again, but to me that really feels like the entire TLA series did not happen.