Yes, the weight thing is a big factor, but I personally don’t think a Ninja 500 is a good starter bike either (too much power). I only meant consider a 500 c.c. if you are extremely over-weight, but I definitely think a 250 is the way to go in a first bike.
I’m 6′, weight ~200 lbs, 31″ inseam and a Nighthawk 250 was just fine for me for learning. Nice and light and it won’t throw you off the bike if you accidentally grab a handful of throttle when you hit a pot-hole or hurl you over the handlebar if you panic and grab a handful of brake. You’ll also be able to hold it up if you over-balance when you stop with the front wheel not pointing straight.