I was rejected by every girl I was interested in (probably two dozen times) from puberty through half of college. I didn't have my first kiss or lose my virginity until age 21. I didn't have my first steady girlfriend until 25 (she's now my wife). I just turned 30.
To be 30 years old now, married, and stably employed... it is such a dream come true. Looking back on my early-20's, it was tough. We're told that age is supposed to be the time of our lives, but it really didn't feel that way. One thing I do believe is that 21st-century society is rough for young men in the 18-mid 20's age range. So much is in flux at that time of our lives and nothing feels stable. That goes double for if you don't have a job. I don't know if you are looking for a lecture but...
First thing you need to do is find a job. Any job. You simply won't be able to provide for yourself otherwise, let alone be an attractive prospect in the dating market.
You say 6'6" like it's a bad thing. Indeed that is REALLY tall. Usually height is considered a bonus but I frankly don't know how that affects your dating prospects. Anyway, it is something out of your control so I would try not to stress about it.
Get to the gym, develop hobbies, be respectful to everyone, introduce yourself to as many attractive women as you can, whatever you do don't swallow the incel lies. If you can make it through the next few years, I really think things will get better.