Although I’m not immediately aware of fatality data broken down the way you’re looking for it, I think it’s safe to say that your understanding is dubious at best.
First, although there were some survivors, one of the worst accidents in aviation history – Pan Am 1736/KLM 4805 in 1977 – could be characterized as a taxiing accident (an impatient KLM pilot – ironically, the airline’s chief flight instructor – started his takeoff roll before the taxiing Pan Am aircraft cleared the runway; 583 fatalities, including 335 on the Pan Am aircraft - which would standing alone rank as one of the 10 worst airline accidents of all time).
Further, accidents that had their genesis in an event that occurred over 10,000 feet can be survivable by many or even most passengers. United 232 in 1989 being the example already emphasized, but some other off-hand examples are United 811 (1989), British Midland 92 (1989), Aloha 243 (1988), Air Canada 797 (1983), and Southern 242 (1977).
Bottom line: the statement that “No seat belt or car seat gonna help you with an airplane crash” is wrong. No matter how ones seeks to redefine “crash”.