I was obsessed with these comics when I was a kid.
I didn't start buying them until 1966. Before that I thought the drawings were too bizarre.
Once I got hooked I wanted to buy all the back issues.Luckily, in those days there was always a garage sale every weekend where some kid would be selling all his comics for a penny each so I went and bought all the issues dating back to the beginning.
It was fun watching the Thing evolve from a melted blob of orange lava into a highly constructed pile of rocks.
I love the colors on these covers too. I think they are by Marie Severin. They are much more muted and moody than the DC superhero comics were.
The thing about Kirby characters is, once he stopped drawing them no one else was ever able to capture the magic. For me, they all died when he left Marvel around 1970.